1. Primary literature refers to the literature produced by people directly according to their practical experience in production, scientific research and social activities. It is also often called the original document, and the recorded knowledge and information are novel, specific and detailed.
2. Secondary literature refers to sorting, concentrating and refining a large number of scattered and disordered primary literature, and sorting and storing it according to a certain logical order and scientific system to make it systematic and convenient for retrieval and utilization.
3. The third kind of literature refers to the literature compiled from a large number of relevant documents through comprehensive analysis and research. Usually, it is formed by collecting a large number of relevant documents around a certain topic through secondary literature retrieval and deeply processing its contents.
Literature can be divided into printing type, miniature type, machine-readable type and audio-visual type according to the carrier form.
Machine-readable literature: a kind of literature that records multimedia information such as words, sounds, graphics and images on media such as disks and optical disks, and uses electronic equipment such as computers.
Zero documents: spoken language, notes, objects, diaries, meeting minutes; A literature: papers, monographs, newspapers, scientific reports, dissertations, patents, standards, etc. The second kind of literature includes catalogues, indexes and abstracts, and the third kind of literature includes abstracts, summaries, special reports, feasibility reports, data manuals, encyclopedias and various textbooks.
Advantages of electronic publications: large amount of information, small volume, high density and space saving; Convenient, fast and accurate access; Fast transmission speed; Relatively cheap; Information resources are used frequently and widely; Intuitive, vivid and interactive; Disadvantages: limited service life and strong technical dependence; The stored information is easily disturbed, destroyed and lost; Copyright and piracy are serious problems.