Primary resources are original sources of information on which other research is based, including documents such as poems, diaries, court records, interviews, surveys, and fieldwork. Primary materials also include research results generated by experiments, which are published as journal articles in some fields of study and sets of data, such as census statistics which have been tabulated, but not interpreted.

Secondary resources describe or analyze the primary sources. Examples of secondary sources include: dictionaries, encyclopedias, textbooks, and books and articles that interpret or review research works.

Tertiary resources list, compile, digest or index primary or secondary sources.  Examples of tertiary resources include indexes, handbooks, digests and almanacs.

If you think about the publication details of the information and consider the following you will often find your answer:

• Timing of the event recorded--If the article was composed close to the time of the event recorded, chances are it is primary material.  For instance, a letter  written by a soldier during the Vietnam War is primary material, as is an article written in the newspaper or a soldier's letter home during the Civil War.  However, an article written analyzing the results of the battle at Gettysburg is secondary material. 
• Rhetorical aim of the written item--Often, an item that is written with a persuasive, or analytical aim is secondary material.   These materials have digested and interpreted the event, rather than reported on it.
• Context of the researching scholar--Primary materials for a critic studying the literature of the Civil War are different from primary materials for a historian studying Civil War prisons. The critic's primary materials are the poems, stories, and films of the era.  The research scientist's primary materials would be the diaries and writings of slave families.

Cycle of Information

Library of Congress Subject Heading Subdivisions

You may see these on library catalog items.  Use a keyword search combining the subdivision with your topic to find each type of material. 

PRIMARY	SECONDARY	TERTIARY
cases correspondence description and travel diaries fiction interview personal narrative pictorial works poetry short stories sources	criticism and interpretation history history and criticism government policy law and legislation moral and ethical aspects political aspects politics and government psychological aspects public opinion religion religious aspects social policy study and teaching	abstracts bibliography chronology classification dictionaries directories encyclopedias guidebooks handbooks, manuals, etc. identification indexes registers statistics index

adapted from University of Wisconsin-Stevens Point University Library