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Reference style overview

Date published by Date updated: September 13, 2016

A reference style is a set of rules on how to refer to your sources in academic writing. Often style guidelines are published in an official handbook containing explanations, examples, and instructions.

Reference styles in English

There are many different reference styles. In the past, each discipline followed its own referencing rules, but today there’s a growing tendency among universities and colleges to choose one single style.

The most popular reference styles in English include APA, Chicago, Harvard, and MLA styles. These styles, among others, are widely used throughout many different academic disciplines.

Differences between styles

There are two main features when it comes to reference styles.

The first is related to how the source is written in your paper’s reference list or “Works Cited” page. Are the titles written in italics? Does a period go at the end of each source on the list?

The second feature is the system for citing a source within the text itself. There are three different in-text citation systems for referring to a source:

  • Author-date system: In this system, you indicate the author and the year of publication directly in the text in the spot where you use the source. An exception here is MLA style, which uses an author-page number system.
  • Numerical system: In this system, you number each of your sources in the reference list and then you use the correct number whenever you want to cite a specific source within your text.
  • Notation system: You write the source (in abbreviated form) in a footnote or endnote.

Below is an overview of the most widely used reference styles:

Reference StyleDisciplineCitation System
APASocial sciencesAuthor-date
HarvardEconomicsAuthor-date
VancouverMedicineNumeric
Chicago AHumanitiesNotation
Chicago BHumanitiesAuthor-date
OSCOLALawNotation
MLAHumanities (esp. language studies)Author-page number
IEEEHard sciences (esp. IT)Numeric
TurabianHumanities (esp. language studies)Notation
TurabianSocial sciencesAuthor-date
AMAMedicineNumeric
ACSChemistryNumeric, Author-page number and Notation
NLMMedicineNumeric
AAASocial studiesNumeric
APSAPolitical scienceAuthor-date
ABNTTechnical StudiesNumeric, Author-date

APA

APA is one of the most popular reference styles in academic writing. APA style was created by the American Psychological Association and was originally used in psychology and social sciences. Today many other disciplines are using it.

APA style works with an author-date system in which you cite the source in an abbreviated form within the text itself and in the literature list you list all the references in full.

Example of APA style source referencing for a book

APA: In-text citation
The book uses success stories from the authors’ own lived experiences to make the case for a creative revolution in the business world (Stewart & Simmons, 2010).
APA: In the literature list
Stewart, D. & Simmons, M. (2010). The Business Playground: Where Creativity and Commerce Collide. Berkeley, USA: New Riders Press.

Harvard

Harvard style is often used in the field of economics. There is no official style guide, which means there are a few variations. A few organizations who have published a style guide are:

Just like APA style, Harvard style is based on an author-date system. It is in fact quite similar to APA style.

Example of Harvard-style source referencing for a book

Harvard: In-text citation
The book uses success stories from the authors’ own lived experiences to make the case for a creative revolution in the business world (Stewart & Simmons 2010).
Harvard: In the literature list
Stewart, D & Simmons, M (2010), The Business Playground: Where Creativity and Commerce Collide, New Riders Press, Berkeley.

Vancouver

Vancouver style was developed by the International Committee of Medical Journal Editors (ICMJE) and is mostly used in the world of medicine. Instead of using an author-date system, Vancouver style works with a numerical system. In the text, the source is indicated using a number while the source details are listed in full in the literature list.

Example of Vancouver style source referencing for a book

Vancouver: In-text citation
The book uses success stories from the authors’ own lived experiences to make the case for a creative revolution in the business world (1).
Vancouver: In the literature list
1. Stewart D, Simmons M. The Business Playground: Where Creativity and Commerce Collide. Berkeley: New Riders Press: 2010.

Chicago

Chicago style is published by The Chicago Manual of Style and is used in the humanities. There are two variations:

  • Chicago A: You indicate the complete source in a footnote or endnote and in a bibliography.
  • Chicago B: You write the source in abbreviated form, in author-date format, in the text itself and you list the source in full in the bibliography.

Example of Chicago style A source referencing for a book

Chicago A: In-text citation
The book uses success stories from the authors’ own lived experiences to make the case for a creative revolution in the business world.1
Chicago A: In the footnote/endnote
1 Dave Stewart and Mark Simmons, The Business Playground: Where Creativity and Commerce Collide (Berkeley: New Riders Press, 2010).
Chicago style A: In the literature list
Stewart, Dave and Mark Simmons. The Business Playground: Where Creativity and Commerce Collide. Berkeley: New Riders Press, 2010.

Example of Chicago style B source referencing for a book

Chicago style B: In-text citation
The book uses success stories from the authors’ own lived experiences to make the case for a creative revolution in the business world (Stewart and Simmons 2010, 22).
Chicago style B: In the literature list
Stewart, Dave and Mark Simmons. 2010. The Business Playground: Where Creativity and Commerce Collide. Berkeley: New Riders Press.

OSCOLA

OSCOLA is used in law schools. It is the predominant referencing style for legal academic writing in English. OSCOLA uses a notation system, including a full source description in the footnote.

Example of OSCOLA source referencing for a book

OSCOLA: In-text citation
The book uses success stories from the authors’ own lived experiences to make the case for a creative revolution in the business world.1
OSCOLA: In the footnote
1 Dave Stewart and Mark Simmons, The Business Playground: Where Creativity and Commerce Collide (New Riders Press, 2010).
OSCOLA: In the literature list
Stewart D and Simmons M, The Business Playground: Where Creativity and Commerce Collide (New Riders Press, 2010)

MLA

MLA style was developed by the Modern Language Association and is especially popular in language studies. MLA uses an author-page number system.

Example of MLA source referencing for a book

MLA: In-text citation
The book uses success stories from the authors’ own lived experiences to make the case for a creative revolution in the business world (Stewart and Simmons 22).
MLA: In the literature list
Stewart, Dave and Mark Simmons. The Business Playground: Where Creativity and Commerce Collide. Berkeley: New Rider Press, 2010. Print.

IEEE

IEEE (Institute of Electrical and Electronics Engineers) is a reference style that is often used in technical studies, like IT and electrical engineering. IEEE style follows examples for specific types of sources. For source types that are not covered in IEEE, Chicago style is used. IEEE uses a numeric system.

Example of IEEE source referencing for a book

IEEE: In-text citation
The book uses success stories from the authors’ own lived experiences to make the case for a creative revolution in the business world (1).
IEEE: In the literature list
1. D. Stewart and M. Simmons, The Business Playground: Where Creativity and Commerce Collide. Berkeley, USA: New Riders Press, 2010.

Turabian

Turabian is a reference style with a lot of similarities to Chicago style. It is specially designed for students who are writing a research paper.

Just like Chicago style, Turabian features a notation system and an author-date system. The notation system is used in humanities (literature, history and the arts) and the author-date system is used in social sciences.

Example of Turabian style notation system source referencing for a book

Turabian style: In-text citation
The book uses success stories from the authors’ own lived experiences to make the case for a creative revolution in the business world.1
Turabian: In the footnote/endnote, first reference to a source
1 Dave Stewart and Mark Simmons, The Business Playground: Where Creativity and Commerce Collide (Berkeley: New Riders Press, 2010), p.22.
Turabian: In the footnote/endnote, subsequent references
1 Stewart and Simmons, The Business Playground: Where Creativity and Commerce Collide, p. 22.
Turabian: In the reference list
Stewart, Dave and Mark Simmons. The Business Playground: Where Creativity and Commerce Collide. Berkeley: New Riders Press, 2010.

Example of Turabian style author-date system source referencing for a book

Turabian style: In-text citation
The book uses success stories from the authors’ own lived experiences to make the case for a creative revolution in the business world (Stewart and Simmons 2010, 22).
Turabian style: In the reference list
Stewart, Dave and Mark Simmons. 2010. The Business Playground: Where Creativity and Commerce Collide. Berkeley: New Riders Press.

AMA

AMA style is often used in medical sciences and is based on a numeric system. The numbering in the text is set in superscript, with the page number included in parentheses.

Example of AMA style source referencing for a book

AMA style: In text-citation
The book uses success stories from the authors’ own lived experiences to make the case for a creative revolution in the business world.1(p3)
AMA style: In the reference list
Stewart D, Simmons M. The Business Playground: Where Creativity and Commerce Collide. Berkeley, USA: New Riders Press; 2010.

ACS

ACS (American Chemical Society) is a reference style that it used primarily in research papers on chemistry. ACS style has three variations for in-text citation. The choice of style depends on the journal. In the overview on page 288 you can find out which variation is used by which journal.

Example of ACS style source referencing for a book

ACS: In text-citation using a footnote
The book uses success stories from the authors’ own lived experiences to make the case for a creative revolution in the business world.1
ACS: In-text citation using a numeric system
The book uses success stories from the authors’ own lived experiences to make the case for a creative revolution in the business world (1).
ACS style: In-text citation using an author-date system
The book uses success stories from the authors’ own lived experiences to make the case for a creative revolution in the business world. (Stewart and Simmons, 2010).

In the reference list, the sources are listed in alphabetical order when the author-date system is used and by number when a numeric system is used.

ACS: In the reference list
Stewart, D.; Simmons, M. The Business Playground: Where Creativity and Commerce Collide; New Riders Press: Berkeley, 2010.

NLM

NLM (National Library of Medicine) is a reference style that is used primarily in the medical world. NLM uses a numeric system.

Example of NLM source referencing for a book

NLM: In-text citation
The book uses success stories from the authors’ own lived experiences to make the case for a creative revolution in the business world [1].
NLM: In the reference list
1. Stewart D, Simmons M. The Business Playground: Where Creativity and Commerce Collide. Berkeley: New Riders Press; 2010.

AAA

AAA (American Anthropological Association) is a reference style that is based on Chicago style and is primarily used in social studies. For source types that are not described in AAA style, Chicago style is used. AAA style uses a numeric system.

Example of AAA source referencing for a book

AAA style: In-text citation
The book uses success stories from the authors’ own lived experiences to make the case for a creative revolution in the business world (1).
AAA style: In the reference list
Stewart, Dave, and Mark Simmons
2010 The Business Playground: Where Creativity and Commerce Collide. Berkeley: New Riders Press.

APSA

APSA (American Political Science Review) is a reference style that is primarily used in political science, with specific rules for documents from the United States government. APSA uses an author-date system.

Example of APSA source referencing for a book

APSA: In-text citation
The book uses success stories from the authors’ own lived experiences to make the case for a creative revolution in the business world (Stewart and Simmons 2014).
APSA: In the reference list
Stewart, Dave, and Mark Simmons. 2010. The Business Playground: Where Creativity and Commerce Collide. Berkeley: New Riders Press.

ABNT

Associação Brasileira de Normas Técnicas is a reference style created by the ABNT, and is primarily used to standardize the formatting of academic papers. This reference style is the main referencing style in Brazil and a well know style in Portugese speeking countries. The norm NB10520 explains that a students who uses ABNT should decide between using a numeric system or an author-date system of referencing. The list of references should be in alphabatical order when the student decides to use the author-date system, or in numerical order, when the numeric system is being used.

Example of ABNT style author-date system source referencing for a book

ABNT: In-text citation
The book uses success stories from the authors’ own lived experiences to make the case for a creative revolution in the business world (Stewart; Simmons, 2014, p. 22).
ABNT: In the reference list
1Stewart, Dave; Simmons, Mark. The Business Playground: Where Creativity and Commerce Collide. Berkeley: New Riders Press, 2014.*

Example of ABNT style numeric system source referencing for a book

ABNT: In-text citation
The book uses success stories from the authors’ own lived experiences to make the case for a creative revolution in the business world (1).
ABNT: In the reference list
(1) Stewart, Dave; Simmons, Mark. The Business Playground: Where Creativity and Commerce Collide. Berkeley: New Riders Press, 2014.
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