For example, for a paper published in a journal, its reference identification number can be:
[1] Zhang San. Exploring the solution to XXX problem [J]. Engineering Technology, 202 1, 49(2): 60-65.
Among them, [1] is the citation number, [J] is the journal paper, [engineering technology] is the journal name, 202 1 is the publication year, and 49(2) is the volume number and the starting and ending page numbers.
Other identification codes referenced are:
M-Monographs (including historical records in ancient books); C- prose collection; N- newspaper articles; D- thesis; R- research report; S standard; Patents; A-precipitation documents in monographs and papers; Z- Other unspecified document types Electronic document types are identified by two letters: DB-Database; Computer program; EB-electronic bulletin electronic document with non-paper carrier, and its carrier type is also indicated in the reference mark: DB/OL-network database DB/MT-magnetic tape database M/CD-CD-ROM book CP/DK-disk software J/OL-network periodical EB/OL-network electronic bulletin.
For different publications and different countries and regions, the specific identification code may be different. What is the specific identification code? You need to consult the corresponding reference format requirements or journal submission guidelines.