A "citation" is the way you tell your readers that certain material in your work came from another source.

When we use another person's idea in our research, we must include a brief notation next to that idea to let our readers know who developed it. This brief notation is called an in-text citation. At the end of our work, we include a fuller notation, which provides details that allow others to identify and locate the source in which we found that idea. This fuller notation is referred to as an end-of-paper citation.

It's important to cite sources you used in your research for several reasons:

  • To show your reader you've done proper research by listing sources you used to get your information
  • To be a responsible scholar by giving credit to other researchers and acknowledging their ideas
  • To avoid plagiarism by quoting words and ideas used by other authors
  • To allow your reader to track down the sources you used by citing them accurately in your paper by way of footnotes, a bibliography or reference list.
Why cite?

Why Cite?

It is the way to tell that some information used in your work was taken from another source.

To give credit to other researcher's idea's and work whether you agree with them or not.

To show readers the materials on which you base your analysis and conclusions.

To tell readers on which materials you based your analysis, findings, and conclusions.

To guide readers to the resources you used so they check and examine them themselves for more information.

Citation is important for academic integrity and doing honest academic work.

Provides information seekers with other useful sources, and make it easier to find that source, these information includes:

Author's name.


The publisher.

The date of publication.

Page numbers, Volume or issue number if information taken from an article published in a journal.

Dos and Don'ts


Whether you are quoting, paraphrasing, copying and pasting, or just referencing, you do need to cite:

  • Anyone else's articulated ideas, arguments, opinions, or experiences.
  • Any artwork, pictures, videos, or other creative works produced by others.
  • Direct quotations of any words written or spoken by others.
  • Unique phrases or terms coined by others.
  • Data, statistics, or facts produced or documented by others.
  • Published research details and results, whether conducted by you or others.
  • And much more!


Listed below are a few items you generally don't need to cite no matter which citation style you use. 

  • Your own personal information or experiences.
  • Your own arguments or opinions.
  • Your own videos, photographs, and other artwork you've created.
  • "Common knowledge"- This one is a little tricky to distinguish.  Here is a general rule of thumb: if the majority of people in your classroom already know the information, then you may not need to cite it.  For example, you may not need to cite the fact that Barack Obama is the past President of the United States.  It's best to think of common knowledge as only the most obvious facts.
  • Generally accepted phrases or terms- this usually applies only to discipline- and audience-specific situations. 

If you're uncertain when not to cite something, check with your instructor, ask a librarian, or seek the answer in the appropriate style manual.

Must Cite:

You must cite:

  • Facts, figures, ideas, or other information that is not common knowledge
  • Ideas, words, theories, or exact language that another person used in other publications
  • Publications that must be cited include:  books, book chapters, articles, web pages, theses, etc.
  • Another person's exact words should be quoted and cited to show proper credit

When in doubt, be safe and cite your source!

Why cite sources?

Giving credit to the original author of thoughts, words, and ideas is an important ethical concept.

  1. To avoid PLAGIARISM: While a bibliography does not prevent plagiarism, it is an important tool in avoiding plagiarism.
  2. BUILDING on research: Pertinent information is gleaned from the ideas of those who came before, and a researcher then produces new knowledge by integrating the ideas of others with her own conclusions. This is the scholarly research process.
  3. TRACING research: According to Joseph Gibaldi, the author of the MLA Handbook for Writers of Research Papers, “in presenting their work, researchers generously acknowledge their debts to predecessors by carefully documenting each source so that earlier contributions receive appropriate credit” (104). This is the basis for all scholarship. It is important that researchers give credit so readers can trace the ideas presented back to the sources.
  4. CONTRIBUTING ideas: Your contribution, as a student, to disciplinary knowledge is the unique ways you interpret and synthesize the words, thoughts, and ideas of authorities. In fact, giving credit to experts and authoritative sources gives your conclusions validity that cannot be achieved by simply stating one's own opinions.
  5. LOCATING additional research: And that is another reason for citations: it allows readers to access the cited materials if they are performing research on that topic
What to Cite?

You must cite:

  • Facts, figures, ideas, or other information that is not common knowledge
  • Ideas, words, theories, or exact language that another person used in other publications
  • Publications that must be cited include:  books, book chapters, articles, web pages, theses, etc.
  • Another person's exact words should be quoted and cited to show proper credit

When in doubt, be safe and cite your source!

Citation styles

Citation styles

There are three major citation styles:

  • Chicago used for many fields
  • MLA used for humanities
  • APA used for social sciences, education, engineering, and business.

Other sciences developed their own styles:

  • CSE for the biological sciences
  • AMA for the biomedical sciences, medicine, and nursing
  • ACS for chemistry
  • AIP for physics, plus other styles for astrophysics and astronomy
  • AMS for mathematics and computer sciences

APA citation style pdf

MLA citation style pdf

Chicago citation style pdf

IEEE citation style pdf

Citation Machine: is a tool to help create fast and easy citations for the most popular styles APA, MLA, Chicago, IEEE, and many more. It is also a plagiarism detection tool, and a tool for finding and fixing grammar errors.

Which style should i use?

These styles are international standards and have style manuals to refer to for further examples.

Author-date referencing styles

Style Subject
APA Psychology, Nursing, Education, Tourism
Chicago Foundation Units, Multidisciplinary
MLA English

Harvard no longer produces a citation guide; please use the Chicago Style Manual.

Notational referencing styles

Style Subject
ACS Chemistry
Footnote Social Sciences, Humanities
IEEE Engineering, Electronics, IT, Computer Science
Legal Law
Vancouver Biomedicine, Health Sciences


Style manual for political Science

Useful tools

Using a citation generator is a very efficient and easy way to create citations in the appropriate format. Try these:

Citation Machine
Citationsy - no ads, great for journal articles
Cite This For Me


One way you can improve your work and stay plagiarism-free is to use Endnote to manage your references.


EndNote X6 guide

EndNote/EndnoteWeb Technical Support & FAQs

S.O.S. Need help with citing

How do i add citations to my PowerPoint presentation?

To cite your sources within a PowerPoint presentation, you can include your references or in-text citations on each slide. You can (a) provide the references verbally, (b) provide a reference list slide at the end of your presentation with corresponding in-text citations, or (c) combine these. 

How to insert citations in Google Docs?

Check out this video

How do I format in-text citations with a one or multiple author(s)? 

How do I cite a source that is quoted or described inside another source? What is a secondary source? 

How do I format reference list and in-text citations for a source with no publication date? 

Is their a APA referencing and citation handout I can download and print?

In-Text citation

Throughout the text, you must always include a proper parenthetical reference (author and the year) unless it is within the same paragraph. Within a paragraph, you do not need to include the year in subsequent references to a study. However, you would need to include the year if the study could be confused with another study cited in the same paragraph. e.g.

In 2000, Smith compared reaction times ...  OR

Smith (2000) compared reaction times ...  OR

In a recent study of reaction times (Smith, 2000) ...  

When PARAPHRASING or referring to an idea contained in another work, APA encourages but does not require one to “provide a page or paragraph number, especially when it would help an interested reader locate the relevant passage in a long or complex text.” (Publication manual, 2010, p. 171)

Where there are TWO AUTHORS, cite both names each time the reference occurs in the text. e.g.

The most recent study (Smith & Jones, 1983) ...  

When there are THREE TO FIVE AUTHORS, cite all the names the first time. From then on, use only the first name followed by et al. (Latin abbreviation for "and others"). e.g.

First citation: Sokolowski, Smith, Jones and Hajid (1983) discovered that ...
Later citations: Sokolowski et al. (1983) also discovered that ...  

When there are SIX OR MORE AUTHORS, cite only the surname of the first author followed by et al. and the year for all citations in text. e.g.

First citation: Hewitt et al. (2001) demonstrated that ...
Later citations: ... as has been shown by Hewitt et al. (2001).

Write out in full the whole name of a GROUP OR ORGANIZATION THAT SERVES AS AUTHOR every time, unless the abbreviation is well known. e.g.

First citation: The police report (Royal Canadian Mounted Police, 1979) ...
Later citations: The RCMP report (1979) ...

Where there is NO AUTHOR, cite the first few words of the title and the date. Put quotation marks around an article title, but italicize the title of a periodical or book. Words in the title are capitalized in reference citations, but not in the reference list. e.g.

Time magazine article ("Brain Breakthrough," 1988) said that ...
It states in the Vancouver Social Services Directory (1988) ...

When there are TWO OR MORE AUTHORS WITH THE SAME SURNAME, include initials to avoid confusion. e.g.

Both G. A. Jones (1984) and B. W. Jones (1986) have studied ...

When there are TWO OR MORE WORKS BY THE SAME AUTHOR IN THE SAME YEAR, "identify works by the same author (or by the same two or more authors in the same order) with the same publication date by the suffixes a, b, c, and so forth, after the year; repeat the year. The suffixes are assigned in the reference list, where these kinds of references are ordered alphabetically by title (of the article, chapter, or complete work). e.g.

several studies (Derryberry & Reed, 2005a, 2005b, in press-a; Rothbart, 2003a, 2003b) (Publication manual, 2010, p. 178)

PERSONAL COMMUNICATIONS (e.g., emails, memos, private letters, telephone conversations, personal interviews etc.) do not provide recoverable data. They are cited in the text only, not in the reference list. Provide the communicator’s initials and surname and as exact a date as possible. e.g.

The methodology is based on neuroscientific research and demonstrates that it is possible to help students strengthen the weak cognitive capacities underlying their learning dysfunctions (V. Tool, personal communication, May 18, 2011).

When the DATE IS UNKNOWN, use the abbreviation ‘n.d.’ – for ‘no date’. e.g.

Bengston (n.d.) shows that …

Multiple In-Text Citations

When multiple studies support what you have to say, you can include multiple citations inside the same set of parentheses.  Within parentheses, alphabetize the studies as they would appear in the reference list and separate them by semicolons.  In running text, you can address studies in whatever order you wish.  Here are two examples:

Studies of reading in childhood have produced mixed results (Albright, Wayne, & Fortinbras, 2004; Gibson, 2011; Smith & Wexwood, 2010).

Smith and Wexwood (2010) reported an increase in the number of books read, whereas Gibson (2011) reported a decrease.  Albright, Wayne, and Fortinbras (2004) found no significant results. (APA Style Blog, 2014)