Web tutorial on using & referencing sources in academic papers

Referencing your sources

As a university student, you can count on having to write papers. When your lecturers give you a writing assignment, they'll expect you to make use of concepts, theories and findings of others. They'll also want to know where you got the information you used in your work.

What is referencing?

When you incorporate source material into your work, you must make it clear to your reader what idea has been taken from which source. Providing identifying information about your sources is called 'referencing' -- also known as 'citing' or 'documenting'.

Why is referencing so important?


'Bôcker' by Johannes Jansson. Licensed under CC BY 2.5 DK.

For several reasons. When referencing your sources, you:

  • give credit to the authors you have cited in your work
  • support your own ideas and conclusions
  • give your work credibility and reliability
  • make your work verifiable
  • allow readers to trace your sources if they wish
  • avoid plagiarism

When is a reference not needed?

When you're dealing with what's known as 'common knowledge'.

Examples of common knowledge

  • World War I lasted from 1914 to 1918
  • There are four seasons in the year
  • Driver fatigue is a cause of accidents
  • In 1509 Erasmus wrote The Praise of Folly
  • Firms maximize profits
  • Many trees shed their leaves in the fall
  • Cinderella lost her glass slipper
  • The Earth is the third planet from the Sun
  • Plato spent most of his life in Athens
  • Abraham Lincoln was the 16th president of the United States

Information qualifies as common knowledge when:

  • it is known widely (e.g. common sense observations, myths, legends, fairy tales, popular expressions)
  • it is not subject to change or dispute
  • it can be found in multiple sources (e.g. scientific facts, historical events, geographical data)

Common knowledge is not limited only to what one 'knows' without needing to consult an encyclopedia or Wikipedia. For example, say you were writing about when Abraham Lincoln issued the Emancipation Proclamation and needed to look up the date to make sure it was 1863. Still, the date of the proclamation could be assumed as common knowledge even if you didn't know it without needing to consult a source. Such information is easy to look up, and the date is not subject to change or dispute -- therefore it's common knowledge.

Likewise, stating that William I, the first Dutch king of the house Orange, was assassinated by a fanatical Catholic named Balthasar Gerards wouldn't require a reference -- even if most Dutch people couldn't tell you who murdered William I, and when this happened. Not to mention non-Dutch people, many of whom wouldn't even know William of Orange ever existed. Again, this is information that is easily found, isn't changeable, and thus can be assumed to be common knowledge.

Field-specific common knowledge

What is considered common knowledge will vary from one 'community' (such as a nation, an ethnic group, a religion, or an academic discipline) to another. For example, in psychology it is common knowledge that chimpanzees recognize themselves in a mirror; an 'outsider' might not know this. Economists who write research papers don't have to cite their sources for the statistical methods they have employed. Such basic knowledge is considered 'common' by any economist reading the paper.

It's difficult sometimes to know whether something is common knowledge in your own field of study. In general, if your lecturer -- in lectures, PowerPoint slides, or handouts -- doesn't acknowledge the source you can safely assume that it's considered common knowledge. The same goes for concepts and theories in your textbook without attribution.


If there is any doubt about whether or not a reference is needed, provide one. It's better to 'overcite' rather than assuming information to be commonly known when in fact it may not be. Keep in mind that if you fail to refererence your sources properly, you run the risk of being accused of sloppy scholarship or even plagiarism.

For more information on plagiarism, and how to avoid it, check the section Using your sources responsibly.