It is not always easy to discern the difference between primary, secondary, and tertiary resources.
For details on this distinction, see this chart.
The following are examples of primary source material:
Primary sources such as diaries, letters and old newspaper articles are invaluable for providing a first-person perspective on exhibits, events and people for your research. To learn more about how to tap into these resources, see the guide on Primary Sources.
Note that with many countries, the majority of primary sources will be in languages other than English, so some degree of fluency in a foreign language may be required. However, you may be able to locate English translations of more prominent documents, often within secondary sources such as books about your subject.
When searching WorldCat for primary sources, combine keyword and/or subject searches on terms such as sources, catalogs, memoirs, diaries, correspondence, papers, personal narratives, or pictorial works. These words will typically appear in the subject headings or notes in records of primary sources.