Исторические источники
Primary source materials are typically defined as "original research papers written by the scientists who actually conducted the study." An example of primary source material is the Purpose, Methods, Results, Conclusions sections of a research paper (in IMRAD style) in a scientific journal by the authors who conducted the study. In some fields, a secondary source may include a summary of the literature in the introduction of a scientific paper, a description of what is known about a disease or treatment in a chapter in a reference book, or a synthesis written to review available literature. A survey of previous work in the field in a primary peer-reviewed source is secondary source information. This allows secondary sourcing of recent findings in areas where full review articles have not yet been published.