Columbia College

Citing Sources

What is a citation?

A citation provides enough information to enable a reader to find the same original source material. Typically, this will include author, title of text, date of publication, place of publication, and publisher.

When to cite sources

You must cite all sources that have directly or indirectly contributed to your analysis, synthesis, and/or argument in the work you submit.


You should quote your sources when it is important to convey the original author’s precise words.

  • If you use the exact text – words, phrases, sentences – you must enclose them in quotation marks and cite.
  • Short quotes – words and phrases – can be embedded into the text you write. Longer quotes – sentences and paragraphs – should be indented and separated from your words.


If you rewrite the original text in your own words, you must cite the source.


If you summarize the argument or data of another author, you must cite the source.


You must cite any text you read that helped you think about your paper even if you do not reference it directly in the text of your paper.

If a person assisted you in clarifying your thoughts – either in conversation or email correspondence – you must cite this source.

One way might be to acknowledge in a footnote connected to your paper’s title or opening sentence your indebtedness to a book or person (noting the date(s) of any relevant conversation or correspondence). Alternatively, for a more significant piece of work – such as an independent study or senior thesis – you can include a paragraph of acknowledgements, noting the range of assistance you received from many people.

Common Knowledge

Common knowledge is information that a reader can reasonably be expected to know. It does not need to be cited.

  • For example, “Barack Obama, the President of the United States, was a student of Columbia College” can be considered to be common knowledge and does not need to be referenced.

However, common knowledge does not include opinion.

  • For example, you might agree with the statement “Columbia College is the best college” – but this is an opinion, not common knowledge and to make this case you would have to cite sources and data that support the supposition.

You should therefore be careful in the assumptions that you make in assessing what might be considered common knowledge.

Moreover, what might be common knowledge in one discipline might not be common knowledge in another discipline. It is important, then, to learn from your instructor the expectations for citing common knowledge in any given class.

If in any doubt, err on the side of caution and cite your source.

How to Cite Sources

Learning to cite correctly can be challenging. There are many different citation styles, which are often discipline- or division-specific. You should seek guidance from your instructor or TA to ensure that you understand the citation expectations for any given class.

An invaluable online resource is Charles Lipson’s book “Cite Right: A Quick Guide to Citation Styles – MLA, APA, Chicago, the Sciences, Professions, and More.” Published in 2008 by University of Chicago Press, this book is available electronically through Columbia Universityiess Libraries.

In addition, Anice Mills, undergraduate services librarian, in 205 Butler Library, can help you create bibliographies and cite sources using a variety of citation styles and software, and can also help you do ethical research with proper citations.

The most common citation styles are:


Modern Language Association (MLA)

Mathematics and Science

American Chemical Society (ACS) – Chemical Sciences

American Institute of Physics (AIP) - Astronomy, Astrophysics, and Physics

Council of Science Editors (CSE) – Biological Sciences

Mathematics and Computer Science

Social Sciences

American Anthropological Association (AAA) – Anthropology and Ethnography

American Psychological Association (APA) – Social Sciences

Chicago Manual of Style – History

Evaluating the Credibility of Your Sources

Remember, your use of sources is a means of supporting the argument you make. This means that the sources you reference need to be credible and authoritative. How do you know that your sources are of value? Start by asking yourself the following questions. For further guidance, Anice Mills, undergraduate services librarian, in 205 Butler Library, can help you evaluate online sources for credibility.

Where was the source published?

  • Is it in a peer-reviewed scholarly journal (i.e. an article that is evaluated by other experts in the field) or published by a university press, professional society, or scientific publisher (all of which also operate peer-review processes)? These texts will have scholarly credibility.
  • Was the source published on-line? This is not necessarily bad, but it will depend on who published it, why it was published, and how you intend to use the material. For example, there are on-line journals that utilize peer-review thus providing greater credibility to the publication. But there are many articles published under the guise of scholarly work, by individuals claiming expertise but which are of highly questionable credibility. If you have doubts about an on-line source, you can discuss it with your instructor or TA and you can elect not to use it.

Who wrote it?

You can undertake brief on-line research into the author. Is the author affiliated with a university or another institution? What else has the author written? Citation databases will also tell you the number of times this source has been cited by other academics, giving you further insight into its credibility.

Is the piece timely and appropriate for its field?

In some disciplines, material can become outdated very swiftly. In others, texts can continue to be considered valuable for longer. You should search for additional texts on the topic to find related sources, sources in which this source is cited, and sources that cite this source in order to get a stronger picture of its intellectual relevance and value.

For whom is the source written?

Is the intended audience a scholarly one? If so, it should have a clear bibliography that you will also be able to consult for further sources.

Will you use the source as a primary or secondary text?

If the material does not measure up to expected standards of scholarly work, it may still be of use to you. But as a primary text – that is to say, a text that needs to be analyzed – rather than a secondary text – which is a text that might support your argument or provide a theoretical framework for your analysis, for example.