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Evaluating & Understanding Resources: Types of Sources

Special Research Guide -- Evaluating and Understanding Library Resources

Three Main Distinctions

Primary sources 
According to the Library of Congress "primary sources are the raw materials of history - original documents and objects which were created at the time under study." They are the "actual records that have survived from the past, such as letters, photographs, articles of clothing."

Secondary Sources
According to Princeton University, "a secondary source interprets and analyzes primary sources. These sources are one or more steps removed from the event." They encompass and either interpret or explain primary data and artifacts.
Note: Peer-reviewed publications generally fall into this category.

Tertiary Sources
According to BMCC, "Tertiary sources consist of information which is a distillation and collection of primary and secondary sources."  Items such as synopsies, indexes, bibliographies and almanacs generally fall into this category.

more on Primary, Secondary, and Tertiary Sources

Primary resourcesare 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 resourcesdescribe 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.

**adapted from University of Wisconsin-Stevens Point University Library