There are several different types of citation formats (also called citation styles or reference systems). The citation format you use influences how your citations appear in your text and how your reference list looks. Some academic disciplines have traditionally preferred specific citation formats. Ask your supervisor whether that's the case for your field.
Broadly speaking, citation formats can be divided into two types:
Author-date-formats are characterized by in-text citations containing the author/creator and the year of publication, both placed in a parenthesis.
Numerical formats are based on assigning a number as the citation in the text. Either one number refers to the same source throughout the text, or else a new number is created for each instance of a citation, referring to a footnote.
Some of the most commonly used citation formats are APA (American Psychological Association), MLA (Modern Language Association), Chicago, IEEE (Institute of Electrical and Electronics Engineers), Harvard, and Vancouver.
The most important part of referencing is to be consistent throughout your text so that your reader is never in doubt about what you are citing, and when you are citing it.
Below you will find a brief introduction to some different citation formats.
Author-date
APA is short for the American Psychological Association, which maintains and updates the format. APA is primarily used within the social sciences and humanities, but has also been adopted elsewhere. It is one of the most widely used citation formats.
In-text citations are placed in parentheses, where the author/creator and the year of publicantion must always be included, although the author can appear outside of the parentheses (e.g., example 3). The reference list is organized alphabetically by the name of the author/creator.
Find the official guidelines for using APA here: The Official Style Blog
Examples:
In-text citation:
In the 'References':
Author-date
MLA is short for the Modern Language Association, who manages and updates the format. MLA is primarily used within the humanities and social sciences. MLA categorized as "author-date" here although "author-title" probably would be more apt, since the title of the source is prioritized in the reference list (called "Works Cited"), and the year is not mentioned in the in-text citations.
In-text citations are placed in parentheses, where the author/creator must be included, although the author can appear without a parenthesis (e.g., example 3). The Works Cited is arranged alphabetically by the name of the author/creator.
Find the official guidelines for using MLA here: MLA Style Center
Examples:
In-text citation:
“It seems that highly cited papers may not make direct contributions to scholarship in a way that is proportional to their citation counts” (Thelwall 10).
Prior research indicates that highly cited articles are often included as a form of agenda-setting (Thelwall).
In the 'Works Cited':
A book:
Neville, Colin. The Complete Guide to Referencing and Avoiding Plagiarism. 2nd ed., Open University Press, 2010.
A book chapter:
Neville, Colin. “The ‘what’ and ‘when’ of Referencing”. The Complete Guide to Referencing and Avoiding Plagiarism, 2nd ed., Open University Press, 2010, pp. 14–27.
An article:
Thelwall, Mike. “Are Classic References Cited First? An Analysis of Citation Order within Article Sections”. Scientometrics, vol. 120, no. 2, Aug. 2019, pp. 723–31, https://doi.org/10.1007/s11192-019-03142-8.
Numerical (Notes and Bibliography)
The Chicago-style is managed by the University of Chicago and consists of two variations, one uses author-date and another using the numerical system. Author-date is often used within the social sciences, while the numerical is often used within the humanities. The difference is mainly in the citation in the text.
In the numerical version, a footnote is created where a longer reference can be found. The first time a source is cited, the reference in the footnote will be the same as in the bibliography, while a shortened version will be used subsequently. The bibliography is arranged alphabetically by the name of the author/creator.
Find the official guidelines for using Chicago here: Chicago Style Quick Guide
Examples:
In-text citation:
“It seems that highly cited papers may not make direct contributions to scholarship in a way that is proportional to their citation counts”¹
Prior research indicates that highly cited articles are often included as a form of agenda-setting¹
In the footnote:
¹Mike Thelwall, “Are Classic References Cited First? An Analysis of Citation Order within Article Sections”, Scientometrics 120, no. 2 (1. august 2019): 10, https://doi.org/10.1007/s11192-019-03142-8.
²Thelwall, “Are Classic References Cited First?”
In the 'Bibliography':
A book:
Neville, Colin. The Complete Guide to Referencing and Avoiding Plagiarism. 2nd ed. Open University Press, 2010.
A book chapter:
Neville, Colin. 2010. 'The ‘what’ and ‘when’ of Referencing'. In The Complete Guide to Referencing and Avoiding Plagiarism, 2nd ed. Open University Press, 2010.
An article:
Thelwall, Mike. 'Are Classic References Cited First? An Analysis of Citation Order within Article Sections'. Scientometrics 120, no. 2 (2019): 723–31. https://doi.org/10.1007/s11192-019-03142-8.
Author-date
The Chicago-style is managed by the University of Chicago and consists of two variations, one uses author-date and another using the numerical system. Author-date is often used within the social sciences, while the numerical is often used within the humanities. The difference is manily in the citations in the text.
In the author-date variation, in-text citations are placed in parentheses, where the author/creator and the year of publication must always be included, although the author/creator can appear outside the parenthesis (e.g., example 3). The reference list is arranged alphabetically by the name of the author/creator.
Find the official guidelines for using Chicago here: Chicago Style Quick Guide
Examples:
In-text citation:
“It seems that highly cited papers may not make direct contributions to scholarship in a way that is proportional to their citation counts” (Thelwall 2019, 10)
Prior research indicates that highly cited articles are often included as a form of agenda-setting (Thelwall 2019).
In the 'References':
A book:
Neville, Colin. 2010. The Complete Guide to Referencing and Avoiding Plagiarism. 2nd ed. Open University Press.
A book chapter:
Neville, Colin. 2010. 'The ‘what’ and ‘when’ of Referencing'. In The Complete Guide to Referencing and Avoiding Plagiarism, 2nd ed. Open University Press.
An article:
Thelwall, Mike. 2019. 'Are Classic References Cited First? An Analysis of Citation Order within Article Sections'. Scientometrics 120 (2): 723–31. https://doi.org/10.1007/s11192-019-03142-8.
Author-year
Unlike most other citation formats, Harvard is not associated with a specific institution or organization that sets guidelines and update standards. Instead, it is more of a general designation for the “author-year” type when used within the natural and social sciences.
In-text citations are placed in parentheses, where the author/creator and the year of publicantion must always be included, although the author can appear outside of the parentheses (e.g., example 3). The reference list is organized alphabetically by the name of the author/creator.
Find a more general guide for using Harvard here: Mendeley's Harvard guide.
Examples:
In-text citation:
“It seems that highly cited papers may not make direct contributions to scholarship in a way that is proportional to their citation counts” (Thelwall, 2019, p. 10).
Prior research indicates that highly cited articles are often included as a form of agenda-setting (Thelwall 2019).
And Thelwall (2019) adds to the empirical foundations for approaching citation counts with suspicion.
In the 'References':
A book:
Neville, C. (2010) The Complete Guide to Referencing and Avoiding Plagiarism. 2nd edn. Maidenhead: Open University Press.
A book chapter:
Neville, C. (2010) ‘The “what” and “when” of referencing’, in The Complete Guide to Referencing and Avoiding Plagiarism. 2nd edn. Maidenhead: Open University Press, pp. 14–27.
An article:
Thelwall, M. (2019) ‘Are classic references cited first? An analysis of citation order within article sections’, Scientometrics, 120(2), pp. 723–731. Available at: https://doi.org/10.1007/s11192-019-03142-8.
Numerical
IEEE is short for Institute for Electrical and Electronics Engineers, which manages and updates the standard. IEEE is primarily used within engineering, computer science and similar fields. In the citation, a number is given that refers to a specific source. In the bibliography, sources are sorted by this number, rather than the author’s name, which is the case with the author-date reference standards.
Find the official guidelines for using IEEE here: IEEE Style Manual
Eksempler:
In-text citation:
“It seems that highly cited papers may not make direct contributions to scholarship in a way that is proportional to their citation counts” [1, p. 10].
Prior research indicates that highly cited articles are often included as a form of agenda-setting [1].
In the 'References':
A book:
[1] C. Neville, The Complete Guide to Referencing and Avoiding Plagiarism, 2nd ed., Maidenhead: Open University Press, 2010.
A book chapter:
[1] C. Neville, 'The ‘what’ and ‘when’ of referencing', in The Complete Guide to Referencing and Avoiding Plagiarism, 2nd ed., Maidenhead: Open University Press, 2010, pp. 14–27.
An article:
[1] M. Thelwall, 'Are classic references cited first? An analysis of citation order within article sections', Scientometrics, vol. 120, no. 2, pp. 723–731, Aug. 2019, doi: 10.1007/s11192-019-03142-8.
Numerical
The Vancouver format is maintained and updated by the NLM, which is the United States National Library of Medicine. The Vancouver system is mainly used within the medical fields. In the citation, a number is given that refers to a specific source. In the bibliography, sources are sorted by this number, rather than the author’s name, which is the case with the author-date reference standards.
Find the official guidelines for using Vancouver here: Citing Medicine
Examples:
In-text citation:
“It seems that highly cited papers may not make direct contributions to scholarship in a way that is proportional to their citation counts” (1)
Prior research indicates that highly cited articles are often included as a form of agenda-setting (1)
In the 'References':
A book:
1. Neville C. The Complete Guide to Referencing and Avoiding Plagiarism, 2nd ed. Maidenhead: Open University Press, 2010.
A book chapter:
1. Neville C. The “what” and “when” of referencing. In: The Complete Guide to Referencing and Avoiding Plagiarism. 2nd ed. Maidenhead: Open University Press; 2010. p. 14–27.
An article:
1. Thelwall M. Are classic references cited first? An analysis of citation order within article sections. Scientometrics. 2019 Aug 1;120(2):723–31.
Ibid. is an abbreviation of the Latin word ibidem, meaning "in the same place". Ibid. is used in in-text citations when referencing the same work multiple times in a row.
Using ibid. can improve the reading experience, especially in author-date citation formats where the in-text citations can be lengthy, but at the same time, it becomes less obvious to the reader what you are citing. You should be aware that in recent years, many citation formats have moved away from using ibid.
Both APA and MLA does not allow the use of ibid., while Chicago recommends against using it.
The guide on this page is merely an overview of the differences between citation formats. Below, you will find links to more detailed guides for each citation format.
The official guidelines can be found at:
The Official Style Blog by the American Psycholgical Association
The official guidelines can be found at:
MLA Style Center by the Modern Language Association
The official guidelines can be found at:
Chicago Style Quick Guide by the University of Chicago
The Harvard format does not have an official style guide by a governing institution or organization.
For a more general guide to using Harvard use this link from the reference management tool Mendeley's guide.
The official guidelines can be found at:
IEEE Style Manual by the Institute for Electrical and Electronics Engineers
The official guidelines for using Vancouver is described in Citing Medicine 2nd ed., see the link below
Citing Medicine published by the United States National Library of Medicine
