According to the content, nature and processing conditions of the documents, documents can be divided into: primary documents, secondary documents and tertiary documents. Primary documents refer to original documents created based on the author's own research results, such as journal articles, research reports, patent specifications, conference papers, etc. Secondary documents are a type of aspects produced after processing and sorting primary documents, such as bibliographies, titles, introductions, abstracts and other search tools. Tertiary literature is literature compiled through comprehensive analysis based on primary and secondary literature. People often refer to this type of literature as the results of "intelligence research", such as reviews, topic reviews, annual subject summaries, progress reports, etc. Data sheet etc. Similarly, there are also divisions of intelligence into primary intelligence, secondary intelligence, and tertiary intelligence.
Primary document
(primary document): refers to the document created or written by the author based on his own research results, regardless of whether he refers to or cites the works of others when creating. , regardless of the material form in which the document appears, it is a primary document. Most articles published in journals and papers presented at scientific conferences are primary documents.
Secondary document
(Secondary document): refers to the product obtained after document workers process, refine and compress primary documents, in order to facilitate the management and utilization of primary documents. And the instrumental literature that is edited, published and accumulated. Search reference books and online search engines are typical secondary documents.
Tertiary document
(tertiary document): refers to the product of extensive and in-depth analysis and research on relevant primary documents and secondary documents. Such as encyclopedias, dictionaries, etc.
Some researchers also add zero-time documents to the above classification, which refers to original documents that have not undergone any processing, such as experimental records, manuscripts, original audio recordings, original videos, conversation records, etc. Zero-time documents play an important role in the preservation of original documents, verification of original data, and verification of original ideas (right holders).