The sequential coding of references means that the documents cited by the author in the paper are coded continuously with Arabic numerals and square brackets in the order in which they appear in the paper, and the serial number is marked as the upper corner or part of the sentence according to the specific situation, and all the documents are arranged in the reference list according to the serial number of the documents appearing in the paper. Expanding the sequential coding of references refers to arranging and coding the documents with Arabic numerals and square brackets in the order in which they appear in the text. Marking method: (1) According to the order in which each document appears in the text, it shall be numbered consecutively with Arabic numerals starting from "1", and the serial number shall be placed in square brackets and marked in the upper right corner of the citation or author. (2) When multiple documents are cited in the same place, the serial numbers of all documents should be listed in square brackets, and the serial numbers should be separated by commas. If consecutive serial numbers (including the next serial number) are encountered, the starting and ending serial numbers are connected by a half word line. (3) When the same document is cited for many times, only one serial number is made up, and the cited page number is placed after square brackets. (4) When a document appears as a sentence component of the text, its serial number should not be expressed in a standard form, but should be parallel to the text.