Documents: papers, reports, etc.

Secondary literature: such as various abstracts.

Three documents: various comprehensive articles

1 .zero document

This is a special form of information source, which mainly includes two aspects: first, the knowledge information before the document is formed, that is, it is the oral conversation of people "out of your mouth and into my ear", and it is the non-documentary information that directly acts on people's sensory organs; Second, unpublished original documents, that is, unpublished original documents, or unpublished books and periodicals, such as letters, manuscripts, records, notes and some books and periodicals for internal use that cannot be obtained through open and formal ordering.

Zero-order documents are generally obtained by oral conversation, visiting exhibitions and attending reports, which not only has certain value in content, but also can make up for the time-consuming shortcomings of general public documents from the objective formation of information to public dissemination.

2. Literary works

This is a document directly produced by people according to their practical experience in production, scientific research and social activities. It is also often called original literature (or a kind of literature), and its recorded knowledge and information are novel, specific and detailed. Primary literature is the literature with the largest number, the largest variety, the freshest content, the widest application and the greatest influence in the whole literature, such as periodical papers, patent documents, scientific and technological reports, conference proceedings, dissertations and so on. These documents have obvious innovative, practical and academic characteristics, which are the main basis for comparative analysis of documents in sci-tech novelty retrieval.

3. Second-hand literature

Secondary literature, also known as secondary literature, is to sort out, concentrate and refine a large number of scattered and disorderly primary literature, and sort out and store it according to a certain logical order and scientific system, so as to make it systematic and convenient for retrieval and utilization. Its main types are directory, index and so on. For example, China Science and Technology Information Catalogue and China Science and Technology Periodical Database. The secondary literature is obviously collectible, systematic and retrievable. It collects not the original literature itself, but the clues of the original literature within a specific range. Its importance lies in greatly reducing the time spent in retrieving the primary literature, and the secondary literature is the main tool used to retrieve the literature in the novelty retrieval work.

4. Three documents

Third-level literature, also known as third-level literature, is a literature compiled from a large number of related documents after 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. There are reviews, comments, summaries, progress, trends, etc. It is of high practical value to comment, summarize and predict the development trend of the existing achievements. In the novelty retrieval work, we can make full use of the review literature reflecting the research trends in a certain field, and understand its research history, development trends and level in a short time, so as to more accurately grasp the technical background of the items to be retrieved and grasp the novelty retrieval points.

In a word, from zero-level literature, first-level literature, second-level literature to third-level literature, it is a different level processing process of knowledge information from dispersion to concentration, from disorder to order, and from erudition to refinement. The quality and quantity of information they contain are different, and they play different roles in improving people's knowledge structure. The zero-level and first-level documents are the most basic information sources and the main objects of document information retrieval and utilization; Secondary literature is a centralized refining and sorting of literature and a tool for literature information retrieval; The three documents are the results of comprehensive analysis and processing of scattered zero documents, first-level documents and second-level documents according to the categories of topics or knowledge. They are highly concentrated literature information, which is not only the object of literature information retrieval and utilization, but also the tool of literature information retrieval.