As described by Patrick J. Schembri (13.12.2007), there are different types of scientific literature including primary, secondary, tertiary, and gray literature.
Primary Research Articles in the Sciences by University of Wisconsin-Madison
Primary Literature
Characteristics:
Report results of original research with new discoveries.
Factual not interpretive
Examples:
Journal articles (peer-reviewed)
Conference papers
Proceedings
Dissertations
Technical reports
Patents
Lab notebooks
Secondary Literature
Characteristics:
Analysis/discussions of original research
Comments on primary literature
Examples:
Books
Book chapters
Magazine articles
Review articles
Tertiary Literature
Characteristics:
Compilation of information from primary and secondary literature
A broad overview of a topic or data
Examples:
Encyclopedia
Handbooks
Textbooks
Gray Literature
Characteristics:
Often scientific or technical
Generally not available through databases or indexes
