BibMe’s Free APA Format Guide & Generator
What is APA?
APA stands for the American Psychological Association, which is an organization that focuses on psychology. They are responsible for creating this specific citation style. The APA is not associated with this guide, but all of the information here provides guidance to using their style.
What is APA Citing?
This citation style is used by many scholars and researchers in the behavioral and social sciences, not just psychology. There are other citation formats and styles such as MLA and Chicago, but this one is most popular in the science fields.
Following the same standard format for citations allows readers to understand the types of sources used in a project and also understand their components.
The Publication Manual of the American Psychological Association is currently in its 6th edition. It outlines proper ways to organize and structure a research paper, explains grammar guidelines, and how to properly cite sources. This webpage, created solely by BibMe to help students and researchers, focuses on how to create APA citations*. For more information, please consult the official Publication Manual of the American Psychological Association, (6th ed.).
We cite sources for many reasons. One reason is to give credit to the authors of the work you used to help you with your own research. When you use another person’s information to help you with your project, it is important to acknowledge that individual or group. This is one way to prevent plagiarism. Another reason why we create citations is to provide a standard way for others to understand and possibly explore the sources we used. To learn more about citations, check out this page on crediting work. Also, read up on how to be careful of plagiarism.
What does it look like?
There are two types of citations. In-text citations are found in the body of the project and are used when adding a direct quote or paraphrase into your work. Reference citations are found in the reference list, which is at the end of the assignment and includes the full citations of all sources used in a project.
Depending on the types of sources you used for your project, the structure for each citation may look different. There is a certain format, or structure, for books, a different one for journal articles, a different one for websites, and so on. Scroll down to find the appropriate citation structure for your sources.
Even though the structure varies across different sources, see below for a full explanation of in-text citations and reference citations.
To learn more about APA referencing, including the American Psychological Association's blog, formatting questions, & referencing explanations, click on this link for further reading on the style. To learn more about BibMe, see the section below titled, “Using BibMe to Create Citations for your Reference List or APA Bibliography.”
In-Text Citations Overview:
When using a direct quote or paraphrasing information from a source, include an in-text citation in the body of your project, immediately following it.
In-text citations may look something like this:
"Direct quote" or paraphrase (Author’s last name, Year, page number).
See the section below titled, “In-Text or Parenthetical Citations,” for a full explanation and instructions.
Full Citations Overview
Each source used to help with the gathering of information for your project is listed as a full citation in the reference list, which is usually the last part of a project.
The structure for each citation is based on the type of source used. Scroll down to see examples of some common source formats.
Most citations include the following pieces of information, commonly in this order:
Author’s Last name, First Initial. Middle initial. (Date published). Title of source. Retrieved from URL
To determine the exact format for your full citations, scroll down to the section titled, “Common Examples.”
If you’re looking for an easy way to create your citations, use BibMe’s free APA citation machine, which automatically formats your citations quickly and easily.
How to Structure Authors
Authors are displayed in reverse order: Last name, First initial. Middle initial. End this information with a period.
Kirschenbaum, M. A.
In an APA citation, include all authors shown on a source. If using BibMe’s APA citation builder, click “Add another contributor” to add additional author names. Our free citation creator will format the authors in the order in which you add them.
If your reference list has multiple authors with the same last name and initials, include their first name in brackets.
Brooks, G. [Geraldine]. (2005). March. New York, NY: Viking.
Brooks, G. [Gwendolyn]. (1949). Annie Allen. New York, NY: Harper & Brothers.
When no author is listed, exclude the author information and start the citation with the title followed by the year in parentheses.
When citing an entire edited book, place the names of editors in the author position and follow it with Ed. or Eds. in parentheses. See below for examples of citing edited books in their entirety and also chapters in edited books.
How to Structure Publication Dates:
Place the date that the source was published in parentheses after the name of the author. For periodicals, include the month and day as well. If no date is available, place n.d. in parentheses, which stands for no date.
How to Structure the Title:
For book titles: Only capitalize the first letter of the first word in the title and the same for the subtitle. Capitalize the first letter for any proper nouns as well. Place this information in italics. End it with a period.
Gone with the wind.
For articles and chapter titles: Only capitalize the first letter of the first word in the title and the same for the subtitle. Capitalize the first letter for any proper nouns as well. Do not italicize the title or place it in quotation marks. End it with a period.
The correlation between school libraries and test scores: A complete overview.
For magazine, journal, and newspaper titles: Write the title in capitalization form, with each important word starting with a capital letter.
The Boston Globe
If you believe that it will help the reader to understand the type of source, such as a brochure, lecture notes, or an audio podcast, place a description in brackets directly after the title. Only capitalize the first letter.
New World Punx. (2014, February 15). A state of trance 650 [Audio file]. Retrieved from https://soundcloud.com/newworldpunx/asot650utrecht
How to Structure Publication Information
For books and sources that are not periodicals, give the city and state (or city and country if outside of the U.S.) for the place of publication. Abbreviate the state name using the two-letter abbreviation. Place a colon after the location.
For journals, magazines, newspapers, and other periodicals, place the volume number after the title. Italicize this information. Place the issue number in parentheses and do not italicize it. Afterwards, include page numbers.
Journal of Education for Library and Information Science,57(1), 79-82.
If you’re citing a newspaper article, include p. or pp. before the page numbers.
How to Structure the Publisher:
The names of publishers are not necessary to include for newspapers, magazines, journals, and other periodicals.
For books and other sources: It is not necessary to type out the name of the publisher exactly as it is shown on the source. Use a brief, but understandable form of the publisher’s name. Exclude the terms publishers, company, and incorporated. Include Books and Press if it is part of the publisher’s name. End this information with a period.
Little Brown and Company would be placed in the citation as: Little Brown.
Oxford University Press would be placed in the citation as: Oxford University Press.
How to Structure Online sources
For sources found online:
- include the URL at the end of the citation
- format it as: Retrieved from URL
- do not place a period after the URL
If you’re citing a periodical article found online, there might be a DOI number attached to it. This stands for Direct Object Identifier. A DOI, or digital object identifier, is a unique string of numbers and letters assigned by a registration agency. The DOI is used to identify and provide a permanent link to its location on the internet. The DOI is assigned when an article is published and made electronically. If your article does indeed have a DOI number, use this instead of the URL as the DOI number is static and never changes. If the source you’re citing has a DOI number, after the publication information add a period and then http://dx.doi.org/10.xxxx/xxxxxx. The x’s indicate where you should put the DOI number. Do not place a period after the DOI number. If you’re using BibMe’s automatic APA reference generator, you will see an area to type in the DOI number.
Lobo, F. (2017, February 23). Sony just launched the world’s fastest SD card. Retrieved from http://mashable.com/2017/02/23/sony-sf-g-fastest-sd-card/?utm_cid=mash-prod-nav-sub-st#ErZKV8blqOqO
Chadwell, F.A., Fisher, D.M. (2016). Creating open textbooks: A unique partnership between Oregon State University libraries and press and Open Oregon State. Open Praxis,8(2), 123-130. http://dx.doi.org/10.5944/openpraxis.8.2.290
Citations and Examples
Citations for Print Books
Author’s Last name, F. M. (Year published). Title of book. Location of publisher: Publisher.
Finney, J. (1970). Time and again. New York, NY: Simon and Schuster.
Looking for an APA formatter? Don’t forget that BibMe’s APA citation generator creates citations quickly and easily.
Notes: When citing a book, keep in mind:
- Capitalize the first letter of the first word of the title and any subtitles, as well as the first letter of any proper nouns.
- The full title of the book, including any subtitles, should be stated and italicized.
Citing an E-book from an E-reader
E-book is short for “electronic book.” It is a digital version of a book that can be read on a computer, e-reader (Kindle, Nook, etc.), or other electronic devices.
Author’s Last name, F. M. (Year published). Title of work [E-reader version]. http://dx.doi.org/10.xxxx/xxxxxx or Retrieved from URL
http://dx.doi.org/10.xxxx/xxxxxx is used when a source has a DOI number. If the e-book you’re citing has a DOI number, use it in the citation. DOIs are preferred over URLs.
Eggers, D. (2008). The circle [Kindle version]. Retrieved from www.amazon.com
Citing an E-book found in a Database and Online
Author’s Last name, F. M. (Year published). Title of work [E-reader version]. http://dx.doi.org/10.xxxx/xxxxxx OR Retrieved from URL
When citing an online book or e-book, keep in mind:
- A DOI (digital object identifier) is an assigned number that helps link content to its location on the Internet. It is therefore important, if one is provided, to use it when creating a citation. In place of the x’s in the doi format, place the 10 digit DOI number.
- Notice that for e-books, publication information is excluded from the citation.
Sayre, R. K., Devercelli, A. E., Neuman, M. J., & Wodon, Q. (2015). Investment in early childhood development: Review of the world bank’s recent experience. https://doi.org/10.1596/978-1-4648-0403-8
Citations for Chapters in Edited Books
Chapter author’s Last name, F. M. (Year published). Title of chapter. In F. M. Last name of Editor (Ed.), Title of book (p. x or pp. x-x). Location: Publisher. http://dx.doi.org/10.xxxx/xxxxxx or Retrieved from URL
Longacre, W. A., & Ayres, J. E. (1968). Archeological lessons from an Apache wickiup. In S. R. Binford & L. R. Binford (Eds.), Archeology in cultural systems (pp. 151-160). Retrieved from https://books.google.com/books?id=vROM3JrrRa0C&lpg=PP1&dq=archeology&pg=PR9#v=onepage&q=archeology&f=false
Citations for Edited Books
Editor, A. A. (Ed.). (Year published). Title of edited book. Location: Publisher.
Gupta, R. (Ed.). (2003). Remote sensing geology. Germany: Springer-Verlag.
Citations for Websites
Citing a general website article with an author:
Author’s Last name, F. M. (Year, Month Day published). Title of article or page. Retrieved from URL
Simmons, B. (2015, January 9). The tale of two Flaccos. Retrieved from http://grantland.com/the-triangle/the-tale-of-two-flaccos/
Citing a general website article without an author:
Article title. (Year, Month Date of Publication). Retrieved from URL
Teen posed as doctor at West Palm Beach hospital: Police. (2015, January 16). Retrieved from http://www.nbcmiami.com/news/local/Teen-Posed-as-Doctor-at-West-Palm-Beach-Hospital-Police-288810831.html
Citations for Journal Articles found in Print:
Author’s Last name, F. M. (Year published). Article title. Periodical Title, Volume(Issue), pp.-pp.
Nevin, A. (1990). The changing of teacher education special education. Teacher Education and Special Education: The Journal of the Teacher Education Division of the Council for Exceptional Children,13(3-4), 147-148.
Citations for Journal Articles found Online
Author’s Last name, F. M. (Year published). Title of article. Title of Journal, volume number(issue number), page range. http://dx.doi.org/10.xxxx/xxxxxx OR Retrieved from URL
Spreer, P., & Rauschnabel, P. A. (2016). Selling with technology: Understanding the resistance to mobile sales assistant use in retailing. Journal of Personal Selling & Sales Management, 36(3), 240-263. http://dx.doi.org/10.1080/08853134.2016.1208100
Notes: When creating your online journal article citation, keep in mind:
- This citation style does NOT require you to include the date of access/retrieval date or database information for electronic sources.
- You can use the URL of the journal homepage if there is no DOI assigned and the reference was retrieved online.
- A DOI (digital object identifier) is an assigned number that helps link content to its location on the Internet. It is therefore important, if one is provided, to use it when creating a citation. All DOI numbers begin with a 10 and are separated by a slash. Don’t forget, BibMe’s free APA generator, which is an APA citation maker, is simple to use!
Citations for a Newspaper Article in Print
Author’s Last name, F. M. (Year, Month Day of Publication). Article title. Newspaper Title, pp. xx-xx.
Rosenberg, G. (1997, March 31). Electronic discovery proves an effective legal weapon. The New York Times, p. D5.
Notes: When creating your newspaper citation, keep in mind:
- Begin page numbers with p. (for a single page) or pp. (for multiple pages).
- Even if the article appears on non-consecutive pages, include all page numbers, and use a comma to separate them. Example: pp. C2, C5, C7-C9.
Citations for Newspapers found Online
Author’s Last name, F. M. (Year, Month Day of Publication). Title of article. Title of Newspaper. Retrieved from URL of newspaper’s homepage
Rosenberg, G. (1997, March 31). Electronic discovery proves an effective legal weapon. The New York Times, Retrieved from http://www.nytimes.com
Notes: When citing a newspaper, keep in mind:
- This style does NOT require you to include the date of access for electronic sources. If you discovered a newspaper article via an online database, that information is NOT required for the citation either.
- Multiple lines: If the URL runs onto a second line, only break URL before punctuation (except for http://).
Citations for Magazines
Citing a magazine article in print:
Author’s Last name, F. M. (Year, Month of publication). Article title. Magazine Title, Volume(Issue), page range.
Tumulty, K. (2006, April). Should they stay or should they go? Time, 167(15), 3-40.
Notes: When citing a magazine, keep in mind:
- You can find the volume number with the other publication information of the magazine.
- You can typically find page numbers at the bottom corners of a magazine article.
- If you cannot locate an issue number, simply don’t include it in the citation.
Citing a magazine article found online:
Author’s Last name, F. M. (Year, Month of publication). Article title. Magazine Title, Volume(Issue). Retrieved from URL
Tumulty, K. (2006, April). Should they stay or should they go? Time, 167(15). Retrieved from http://content.time.com/time/magazine/article/0,9171,1179361,00.html
Notes: When creating an online magazine citation, keep in mind:
*The volume and issue number aren’t always on the same page as the article. Check out the other parts of the website before leaving it out of the citation.
Citations for Films
Producer’s Last name, F. M. (Producer), & Director’s Last name, F. M. (Director). (Release Year). Title of motion picture [Motion picture]. Country of Origin: Studio.
Bender, L. (Producer), & Tarantino, Q. (Director). (1994). Pulp fiction [Motion picture]. United States: Miramax.
Citations for Films & Videos from YouTube
Person who posted the video’s Last name, F. M. [User name]. (Year, Month Day of posting). Title of YouTube video [Video file]. Retrieved from URL
If the name of the individual who posted the YouTube video is not available, begin the citation with the user name and do not place this information in brackets.
Smith, R. [Rick Smith] (2013, September 20). Favre to Moss! [Video file]. Retrieved from https://www.youtube.com/watch?v=gOP_L6hBjn8
Citations for Photographs
Citing a photograph found in a publication or museum:
Photographer’s Last name, F. M. (Photographer). (Year, Month Day of Publication). Title of photograph [Photograph]. City, State of Publication or Museum: Publisher/Museum.
Roege, W. J. (Photographer). (1938). St. Patrick’s Cathedral, Fifth Avenue from 50th St to 51st Street [Photograph]. New York, NY: New York Historical Society.
Citing a photograph retrieved online:
Photographer, A. (Photographer). (Year, Month Day of Publication). Title of photograph [Digital image]. Retrieved from URL
Ferraro, A. (Photographer). (2014, April 28). Liberty enlightening the world [Digital image]. Retrieved from https://www.flickr.com/photos/afer92/14278571753/in/set-72157644617030616
Citations for TV/Radio Broadcasts
Writer, F. M. (Writer), & Director, F. M. (Director). (Year of Airing). Episode title [Television series episode]. In F. M. Executive Producer’s Last name (Executive Producer), TV series name. City, State of original channel: Channel.
Kand, K. (Writer), & Fryman, P. (Director). (2006). Slap bet [Television series episode]. In C. Bays (Executive Producer), How I met your mother, Los Angeles, CA: CBS.
TV/Radio Broadcasts found Online:
Writer, F. M. (Writer), & Director, F. M. (Director). (Year of Airing). Episode title [Television series episode]. In F. M. Executive Producer’s Last name (Executive Producer), TV series name. Retrieved from URL
Kand, K. (Writer), & Fryman, P. (Director). (2006). Slap bet [Television series episode]. In C. Bays (Executive Producer), How I met your mother. Retrieved from https://www.hulu.com/watch/1134858#i0,p30,d0
Note: When citing a TV show or episode, keep in mind:
*IMDB is a great resource for finding the information needed for your citation (Director, Writer, Executive Producer, etc.) This information can also be found in the opening and closing credits of the show.
Citations for Interviews:
A personal interview should NOT be included in a reference list. They are not considered recoverable data (they cannot be found by a researcher). You should reference personal interviews as in-text citations instead.
(J. Doe, personal communication, December 12, 2004)
Citations for Encyclopedia Entries
Author’s Last name, F. M. (Publication Year). Entry title. In F. M. Last name of Editor (Ed.), Title of encyclopedia (pp. xx-xx). City, State abbreviation or Country: Publisher.
Kammen, C., & Wilson, A. H. (2012). Monuments. Encyclopedia of local history. (pp. 363-364). Lanham, MD: AltaMira Press.
How to Reference a Lecture
This style of reference would be used if you were citing a set of notes from a lecture (e.g. PowerPoint or Google slides provided by your instructor).
Citing online lecture notes or presentation slides:
Author’s Last name, F. M. (Publication year). Name or title of lecture [Lectures notes or PowerPoint slides]. Retrieved from URL
Saito, T. (2012). Technology and me: A personal timeline of educational technology [PowerPoint slides]. Retrieved from http://www.slideshare.net/Bclari25/educational-technology-ppt
Tip: If you want to cite information from your own personal notes from a lecture, this is considered personal communication. It is considered personal communication since the lecture notes may not be available online for others outside of the class to access. Refer to it only in the body of your essay or project. You can follow the style guide for personal communication available in the Interview section.
In-Text and Parenthetical Citations
What is an In-Text Citation or Parenthetical Citation?
The purpose of in-text and parenthetical citations is to give the reader a brief idea as to where you found your information, while they’re in the middle of reading or viewing your project. You may include direct quotes in the body of your project, which are word-for-word quotes from another source. Or, you may include a piece of information that you paraphrased in your own words. These are called parenthetical citations. Both direct quotes and paraphrased information include an in-text citation directly following it. You also need to include the full citation for the source in the reference list, which is usually the last item in a project.
In-Text Citations for Direct Quotes
The in-text citation is found immediately following the direct quote. It should include the page number or section information to help the reader locate the quote themselves.
Buck needed to adjust rather quickly upon his arrival in Canada. He states, “no lazy, sun-kissed life was this, with nothing to do but loaf and be bored. Here was neither peace, nor rest, nor a moment’s safety” (London, 1903, p. 25).
In-Text Citations for Paraphrased Information:
When taking an idea from another source and placing it in your own words, it is not necessary to include the page number, but you can add it if the source is large and you want to direct readers right to the information.
At the time, papyrus was used to create paper, but it was only grown and available in mass quantities in Egypt. This posed a problem for the Greeks and Romans, but they managed to have it exported to their civilizations. Papyrus thus remained the material of choice for paper creation (Casson, 2001).
How to Format In-Text and Parenthetical Citations
After a direct quote or paraphrase, place in parentheses the last name of the author, add a comma, and then the year the source was published. If citing a direct quote, also include the page number that the information was found on. Close the parentheses and add a period afterwards.
If the author’s name is included in the text of your project, omit their name from the in-text citation and only include the other identifying pieces of information.
Smith states that, “the Museum Effect is concerned with how individuals look at a work of art, but only in the context of looking at that work along with a number of other works” (2014, p. 82).
If your source has two authors, always include both names in each in-text citation.
If your source has three, four, or five authors, include all names in the first in-text citation along with the date. In the following in-text citations, only include the first author’s name and follow it with et al.
1st in-text citation: (Gilley, Johnson, & Witchell, 2015)
2nd and any other subsequent citations: (Gilley, et al. 2015)
If your source has six or more authors, only include the first author’s name in the first citation and follow it with et al. Include the year the source was published and the page numbers (if it is a direct quote).
1st in-text citation: (Jasper, et al., 2017)
2nd and any other subsequent citations: (Jasper, et al., 2017)
If your source was written by a company, organization, government agency, or other type of group, include the group’s name in full in the first in text citation. In any in-text citations following it, it is acceptable to shorten the group name to something that is simple and understandable.
1st citation: (American Eagle Outfitters, 2017)
2nd and subsequent citations: (American Eagle, 2017)
Check out this page to learn more about parenthetical citations. Also, BibMe creates your parenthetical citations quickly and easily. Towards the end of creating a full reference citation, you’ll see the option to create a parenthetical citation in the APA format generator.
Your Reference List
The listing of all sources used in your project are found in the reference list, which is usually the last page or part of a project. Included in this reference list are all of the sources you used to gather research and other information.
It is not necessary to include personal communications in the reference list, such as personal emails or letters. These specific sources only need in-text citations, which are found in the body of your project.
All citations, or references, are listed in alphabetical order by the author’s last name.
If you have two sources by the same author, place them in order by the year of publication.
Thompson, H. S. (1971). Fear and loathing in Las Vegas: A savage journey to the heart of the American dream. New York, NY: Random House.
Thompson, H. S. (1998). The rum diary. New York, NY: Simon & Schuster.
If there are multiple sources with the same author AND same publication date, place them in alphabetical order by the title.
Dr. Seuss. (1958). The cat in the hat comes back. New York, NY: Random House.
Dr. Seuss. (1958). Yertle the turtle. New York, NY: Random House.
If a source does not have an author, place the source in alphabetical order by the first main word of the title.
Need help creating the citations in your APA reference list? BibMe creates your citations by entering a keyword, URL, title, or other identifying information.
How to Format Your Paper in APA:
Need to create APA format papers? Follow these guidelines:
In an APA style paper, the font used throughout your document should be in Times New Roman, 12 point font size. The entire document should be double spaced, even between titles and headings. Margins should be 1 inch around the entire document and indent every new paragraph using the tab button on your keyboard.
Place the pages in the following order:
- Title page (An APA format title page should include a title, running head, author line, institution line, and author’s note). (Page 1)
- Abstract page (page 2)
- Text or body of research paper (start on page 3)
- Reference List
- Page for tables (if necessary)
- Page for figures (if necessary)
- Appendices page (if necessary)
Page numbers: The title page counts as page 1. Number the pages afterwards using Arabic numbers (1, 2, 3, 4…).
What is a running head?
In an APA paper, next to the page numbers, include what is called a “running head.” The running head is a simplified version of the title of your paper. Place the running head in the top left corner of your project and place it in capital letters.
On the title page only, include the phrase: Running head
Title page example:
- Running head: QUALITY LIBRARY PROGRAMS
For the rest of the paper or project, do not use the term, Running head.
Example of subsequent pages:
Microsoft Word, Google Docs, and many other word processing programs allow you to set up page numbers and a repeated running head. Use these tools to make this addition easier for you!
If you’re looking for an APA sample paper, check out the other resources found on BibMe.
Using BibMe to Create Citations for your Reference List or Bibliography
Looking to cite your sources quickly and easily? BibMe can help you generate your citations; simply enter a title, ISBN, URL, or other identifying information.
See more across the site here and if you’d like to cite your sources in MLA format, check out BibMe’s MLA page. Other citation styles are available as well.
Background Information and History of APA:
The American Psychological Association was founded in 1892 at Clark University, in Worcester, Massachusetts. APA style format was developed in 1929 by scholars from a number of different scientific fields and backgrounds. Their overall goal was to develop a standard way to document scientific writing and research.
Since its inception, the Style Manual has been updated numerous times and it is now in its 6th edition. The 6th edition was released in 2010. In 2012, APA published an addition to their 6th edition manual, which was a guide for creating citations for electronic resources.
Today, there are close to 118,000 members. There is an annual convention, numerous databases, and journal publications. Some of their more popular resources include the database, PsycINFO, and the publications, Journal of Applied Psychology and Health Psychology.
*Disclaimer: The American Psychological Association was not involved in the making of this guide.
Helpful Tips for Your Citation
Our citation guides provide detailed information about all types of sources in MLA, APA, Chicago and Turabian styles.
If required by your instructor, you can add annotations to your citations. Just select Add Annotation while finalizing your citation. You can always edit a citation as well.
Remember to evaluate your sources for accuracy and credibility. Questionable sources could result in a poor grade!
Sagarin, B. J., & Lawler-Sagarin, K. A. (2005). Critically evaluating competing theories: An exercise based on the Kitty Genovese murder. Teaching of Psychology, 32(3), 167–169. https://doi.org/10.1207/s15328023top3203_8
What is a DOI?
Some library databases, such as PsycARTICLES and PsycINFO, list a Digital Object Identifier (DOI) for individual articles. A DOI is a unique identifying number for an article. In the database record for an article, you will see an element that looks like this, which you should include at the end of your APA reference, preceded by "https://doi.org/":
This link will allow a reader to link to doi.org for more information about the article.
However, the APA Style Guide to Electronic References (2012, p. 5) notes that it is still acceptable to use the older style of DOI format in a citation, for example:
Amidzic, O., Riehle, H. J., & Elbert, T. (2006). Toward a psychophysiology of expertise: Focal magnetic gamma bursts as a signature of memory chunks and the aptitude of chess players. Journal of Psychophysiology, 20(4), 253-258. doi:10.1027/0269-8803.20.4.253