Periodical, published regularly. Such as weekly, monthly, bimonthly, monthly, quarterly, biannual, annual, etc. Publications shall be published by periodical publishing units established according to law. Periodical publishing units must be approved by the General Administration of Press and Publication, hold a unified serial publication number in China, and obtain a periodical publishing license.
Taking the news and publication volume of Encyclopedia of China as the representative, the periodicals are divided into four categories:
(1) General periodicals, which emphasize knowledge and interest, have a wide readership, such as People's Pictorial and Popular Movies in China, Time and Reader's Digest in the United States, etc.
(2) Academic journals, which mainly publish academic papers, research reports, summaries and other articles, are mainly aimed at professional workers.
(3) Industry periodicals, which mainly report the products, market conditions, management progress and trends of all walks of life, such as motorcycle information in China, Japanese furniture, office equipment and products.
(4) Search periodicals, such as national newspaper index, national new bibliography, American chemical abstracts, etc.