The types of references (i.e. citations) are identified by single letters, and R represents research reports. Other marks in the references are: m- monograph, C- thesis, N- newspaper article, J- journal article, D- dissertation, S- standard, P- patent. If the serial number of a reference appearing as text needs to be followed by a page number or a page number range, the page number or page number range should also be superscript. Authors and editors need to carefully check the serial numbers of references under the sequential coding system, so that the serial numbers are consistent with the list of references after the marked documents are exactly the same. In addition, the page number or page number range of references should also be accurate.