"Primary sources consist of unpublished documents such as letters, diaries, minutes of meetings, government reports, tape recordings, and sketches, as well as sources such as books, magazines, and newspaper articles that were published during the time of the event or person being studied. Perhaps the easiest way to explain the meaning of a "primary source" is to define what it is not: a primary source is not a secondary source. Secondary sources report on, analyze, summarize, or distill in some way information garnered from primary sources. They are derived from primary sources...

... There are many types of and formats for primary sources. Sometimes the types of resources overlap: for example, an original photograph might be available in the special collections area of a library, on the web, or reproduced in a book. The types of primary sources you use for your research will depend on what your topic is, what is available within your own library or on the web, and whether or not you are able to visit other libraries or repositories."

- From Leslie Stebbins (2005) Student guide to research in the digital age: How to locate and evaluate information sources, Santa Barbara: ABC-CLIO, 62-63.