Primary, secondary and tertiary sources   Tags: primary, publications, resources, secondary, tertiary  

A secondary source is information about primary, or original, information, which usually has been modified, selected, or rearranged for a specific purpose or audience. It is not always easy to discern the difference between primary and secondary sources. Examples include biographies, histories, monographs, review articles, textbooks, and any index or bibliography used to locate primary sources.

Secondary sources are less easily defined than primary sources. What some define as a secondary source, others define as a tertiary source. Nor is it always easy to distinguish primary from secondary sources. A newspaper article is a primary source if it reports events, but a secondary source if it analyses and comments on those events. In science, secondary sources are those which simplify the process of finding and evaluating the primary literature. They tend to be works which repackage, reorganize, reinterpret, summarise, index or otherwise "add value" to the new information reported in the primary literature. More generally, secondary sources

• describe, interpret, analyze and evaluate the primary sources
• comment on and discuss the evidence provided by primary sources
• are works which are one or more steps removed from the event or information they refer to, being written after the fact with the benefit of hindsight.

• bibliographies (may also be tertiary)

• biographical works

• commentaries

• dictionaries and encyclopedias (may also be tertiary)

• dissertations or theses (more usually primary)

• handbooks and data compilations (may also be tertiary)

• history

• indexing and abstracting tools used to locate primary & secondary sources (may also be tertiary)

• journal articles, particularly in disciplines other than science (may also be primary)

• monographs (other than fiction and autobiography)

• newspaper and popular magazine articles (may also be primary)

• review articles and literature reviews

• textbooks (may also be tertiary)

• treatises

• works of criticism and interpretation