In academic papers, document marking symbols are very important. According to GB3469-83 Document Types and Document Carrier Codes, the common abbreviations of reference types are: monograph [M], conference proceedings [C], newspaper articles [N], journal articles [J], dissertations [D], reports [R], standards [S], patents [P] and paper columns.

When referring to documents, you need to use the corresponding comment symbols. For example:

-Journal articles: [J];

-Dissertation: [d];

-Report: [R];

-standard: [s];

-patent: [p];

-Documents precipitated in the collection: [a];

—— Precipitated documents in monographs and anthologies, and historical records and local records in ancient books: [M];

-newspaper article: [N].