The distinction between primary, secondary and tertiary sources hinges on how far from the original event or phenomenon the information source is created. Is it first-hand knowledge? A second-hand interpretation? A third-hand synthesis and summary of what is known?
Why is this important? Because different kinds of research call for using primary, secondary, and tertiary sources in different ways. For example, a research paper usually requires a combination of primary and secondary sources.
The video below describes in greater detail more about the differences between primary, secondary and tertiary sources, and how each is used in research.
|Topic||Example of an Appropriate Primary Source|
|Ancient Greek drama||Ancient Greek plays; ancient Greek essays about drama.|
|Learning styles of children||Data from observational studies; data from experiments|
|Performance of a company||Annual reports; SEC filings|
|Ancient Chinese textiles||Contemporary paintings of the textiles; an ancient Chinese manual on weaving|
|Hmong immigrants' attitudes toward libraries||Recordings or transcripts of interviews with Hmong immigrants|
|President F. Roosevelt's speeches||Recordings of his Fireside Chat radio broadcasts; his speech notes|
|Sinking of a ship in 1920||Newspapers and newsreels about the event; a memoir|
|Effects of different bleach concentrations on a virus||Data from an experiment|
Unlike articles and books, primary sources are often unpublished, and that can make them harder to find. But there are many tools to help you locate them.
You may have noticed that there is an overlap between the topic of gray literature and the topic of primary sources. Long story short - Not all Gray Literature is Primary Sources, and not every Primary Source is an example of Gray Literature. But here are some examples of things that are both: