Find & Discover

Thomas Patch, The Golden Asses, The Lewis Walpole Library, Yale University
Thomas Patch. The Golden Asses. Lewis Walpole Library. Yale University.

How do scholars and researchers find primary sources? There are many discovery tools, search strategies, and practical considerations that are especially useful when conducting research with primary sources.

Discovery Tools
A group studies Sunlight in a Cafeteria, by Edward Hopper (1882-1967) in the Yale University Art Gallery

Search Strategies
Studying a document in Cherokee from the Kilpatrick Collection of Cherokee Manuscripts, Beinecke Rare Book and Manuscript Library WA MSS S-2707

Primary, secondary, and tertiary sources

While primary sources are often the core of a research paper or project, researchers also depend on other types of sources to provide context, perspective, and support for the analysis of primary sources.

Secondary sources analyze, interpret, and evaluate primary sources. Secondary sources typically reference or summarize primary sources and other secondary sources. Examples of secondary sources include scholarly works, textbooks, journal articles, histories, and biographies.

Tertiary or reference sources summarize and synthesize information about a topic from other sources. Tertiary sources can be a useful tool for locating primary and secondary sources. Examples of tertiary sources include encyclopedias and dictionaries, chronologies, almanacs, directories, indexes, and bibliographies.

Deciding whether a source is primary or secondary is sometimes confusing. In fact, many sources can be either primary or secondary depending on the context of the research and of the source itself. For example, a medical journal article from the early 20th century looks like a secondary source but could also be used as a primary source when writing about the history of medicine. In this context, a medical journal article can be used as evidence of contemporary views of medicine during this time period. For more information on types of primary sources, explore Identify Types & Formats.

Examples of primary, secondary, and tertiary sources by subject discipline

Subject

Primary

Secondary

Tertiary

Art history

Painting, photograph, film

Critical review of an artist’s work

Encyclopedia article on the artist

Biology

A bird specimen

A scholarly book on bird behavior

BIOSIS Previews database; The Ornithologist’s Dictionary

Chemistry

Article presenting original scientific research, unpublished data, correspondence and original notes

Review of recent research in the field summarizing new articles, patents, etc.

Handbook of basic tables for chemical analysis

History

Diary, correspondence, photograph, census data

Book about the American industrial revolution and its effect on rural culture

Timeline of the American industrial revolution

Literature

Novel, poem, manuscript, correspondence

Essay analyzing an author’s writing process

Handbook of twentieth-century authors

Music

Manuscript score, print edition from composer’s lifetime, first recording of a jazz piece

Essay analyzing the music or the composer’s compositional process, recording of a work without composer’s input

Thematic catalog of a composer’s works; discography of a jazz artist

Political science

Treaty, government document or memo

Diplomatic history textbook

Chronology of treaties