Literally, a reference is a document cited in the writing process, such as an article or a book. However, according to the definition of GB/T 77 14-20 15, the reference after the text refers to the relevant literature information resources cited for writing or editing papers and works.

According to the requirements of China Academic Journals (CD-ROM Edition) Retrieval and Evaluation Data Standard (Trial) and China Social Science Journals Arrangement Standard (Revised Edition), many publications distinguish between references and annotations, and define annotations as "words that further explain or supplement a certain content in a text", which are listed at the end of the article, separated from references or placed at the footer.

According to GB3469-83 "File Types and File Carrier Codes", reference file types and file types are identified by a single letter:

Monograph m; Newspaper n; Journal j; Patent document p; Compilation g; Ancient books o; Technical standards;

Dissertation d; Scientific and technological report; Reference tool k; Search tool w; File b; Tape a;

Chart q; Record l; Product sample x; Video tape v; Meeting minutes; Chinese translation test;

Music score I; Movie y; Manuscript h; Microfilm u; Slide z; Miniature flat film f; Other e.