APA-periodicals are widely used in social sciences. MLA-humanities is used more. GB/T77 14: (China) The national standard code consists of capital Chinese phonetic letters. The code name of the mandatory national standard is GB, and the code name of the recommended national standard is GB/T. Citation principle: the principle of necessity. One is to quote the published literature directly read by the author and retrieved by computer, that is, the original literature. Second, it is closely related to the theme of the paper. Thirdly, it can quote, refute and support the arguments, arguments, charts and data in the paper. Fourthly, it is directly related to the materials, methods, results and conclusions in the paper. Fifthly, the literature citing different viewpoints should be representative. Sixth, the documents that cite the same viewpoint should be representative. Exclude documents with common sense, outdated information and poor timeliness, as well as private letters and internal handouts that are not published publicly.