Books UNESCO 1964 stipulates that printed matter with more than 49 pages is called a book and printed matter with 5-49 pages is called a booklet, but the regulations vary from country to country. Generally, it refers to binding into a book and systematically describing the article in chapters. Generally, the contents are summarized and reorganized publications, which belong to three documents. The content system is in-depth, but the publishing cycle is long, so the information contained in the periodicals published at the same time is newer than that in books. The types of books include encyclopedias, manuals, dictionaries, guides, monographs (reflecting the whole picture of a certain subject, in which there are a lot of concentrated materials) and teaching materials (many standard books of a certain subject are also named after this, which are actually reference books, not teaching books); Other comprehensive books have the names of the latest progress, progress and contemporary trends. Documents other than periodicals and books. Such as monographs or conference proceedings (conference materials compiled and published after national or international conferences reflect the work of contemporary famous scientists and have high reference value; Some are published in the form of books, some are attached to publications or published separately as special issues and supplements), literature compilations (periodicals and papers published at conferences), scientific and technological reports (official reports on research on a certain subject), government publications, patent documents, standard documents, catalogues or samples of product information, dissertations, translated documents (such as scientific news translated and published in China and selected publications published in American medical journals) and technical files.