Primary sources generally represent the object of study (e.g. a novel; a film) or first hand accounts or representations of the object of study (e.g. the correspondence of an historical figure or the autobiography of a battle survivor; statistical or other data, etc.)
- Original source materials on which the research of others is based
- Information in primary sources is the "raw data" and has not been evaluated or interpreted by others
- They are contemporaneous with (from the same time period as) the object of study
- Includes things like: research results, statistics, literary works, diaries/autobiographies, interviews, speeches, etc.
Secondary sources can provide commentary on a primary source (e.g. a critical monograph on Dostoevsky's religious motifs) or use primary (and secondary) source material to support a position (e.g. Trotsky's military acumen has been highly over-rated by historians, etc.).
- Publications (articles, books, dissertations, proceedings, reports, etc.) that describe, interpret, analyse or comment on primary sources
- Include things like biographies, critical works, review articles, journal articles, etc.
Tertiary sources are sources that bring together or "manage" multiple secondary sources. Often they are edited works or are anonymous. Examples would be subject-oriented dictionaries or encyclopedias, print or electronic indexes, library "pathfinder" pages, etc.
- Examples would include: directories, chronologies, almanacs, encyclopedias, indexes, bibliographies, etc.
For academic study, scholarly sources are generally preferred, as are the use of primary and secondary (rather than tertiary) sources as support for one's thesis. However, because a primary source is really defined by its relation to the object of study, sources should never be exluded arbitrarily.
For example, if one is studying teen culture, then fanzines, soft-drink commercials and tatoos could be important primary sources. Likewise, someone studying Stalinist culture might use the Great Soviet Encyclopedia as a primary source (as a product of the culture), where it would be a tertiary source for others. Critical works by the literary critic/theorist Mikhail Bakhtin could be primary sources for a biographer of Bakhtin, but secondary sources for a literary scholar.