Primary sources can include: artifacts, audio recordings, diaries, internet communication, interview, letters, peer-reviewed journal articles, original documents, patents, photos, proceedings, records of organizations, speeches, videos, survey results, works of art, web sites.
Secondary sources are sources and information that is produced "after the fact" and are often interpretive in nature. Examples of secondary sources include: bibliographies, biographies, criticisms, commentaries, dictionaries, encyclopedias, histories, journal articles, monographs (except fiction and autobiographies), textbooks, websites.
Tertiary sources combine elements of primary and secondary sources. Examples of tertiary sources include: almanacs, bibliographies, dictionaries, encyclopedias, fact books, guidebooks, manuals, textbooks.
Do you notice that some items can be considered primary, secondary, and tertiary? Sometimes it is difficult to determine what is original and what is an interpretation or distillation of an original work.
Here is a great summary from University of Maryland that compares the three types of sources:
Teaching and Learning Services. "Primary, Secondary and Tertiary Sources." University of Maryland Libraries.
Looking for primary sources? Try our Special Collections.
Other sources for evaluating primary source materials can be found below: