Scientific literature is divided into two basic categories - "primary" and "secondary".
| Primary Source | Secondary Source | |
| DEFINITIONS | Original materials that have not been filtered through interpretation or evaluation by a second party. | Sources that contain commentary on or a discussion about a primary source. |
| TIMING OF PUBLICATION CYCLE | Primary sources tend to come first in the publication cycle. | Secondary sources tend to come second in the publication cycle. |
| FORMATS--depends on the kind of analysis being conducted. | Conference papers, dissertations, interviews, laboratory notebooks, patents, a study reported in a journal article, a survey reported in a journal article, and technical reports. | Review articles, magazine articles, and books |
| Example: Scientists studying Genetically Modified Foods. | Article in scholarly journal reporting research and methodology. | Articles analyzing and commenting on the results of original research; books doing the same |
EXAMPLES OF PRIMARY AND SECONDARY SOURCES
| Primary Source | Secondary Source |
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Source: The Evolution of Scientific Information (from Encyclopedia of Library and Information Science, vol. 26). Adapted from The University of Albany
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