1 .zero document
This is a special form of information source, which mainly includes two aspects: first, the knowledge information before the file is formed, that is, it is the non-file information of human oral conversation and direct action on human sensory organs; Second, the original documents that have not been publicly published in the society, or various books and periodicals that have not been officially published, such as letters, manuscripts, records, notes, etc., also include some books and periodicals that are used internally and cannot be obtained through public 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 largest, most diverse, most widely used and most influential literature in the whole literature system, such as periodical papers, patent documents, scientific reports, conference proceedings, dissertations and so on. These documents are innovative, practical and academic, 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 catalog, index and abstract. 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 searching a document. Secondary literature is the main tool used to retrieve literature in novelty retrieval.
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, comments, progress, trends and so on. These documents comment, summarize and predict the development trend of existing achievements, which has high practical value. 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 short, from zero-level documents, first-level documents, second-level documents to third-level documents, 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.