What do the [J][D] and so on in the references at the end of the paper mean?

J stands for journal article and D stands for dissertation.

Reference type and document type, according to the provisions of GB3469-83 "Document Type and Document Carrier Code", are identified by single letters: monograph M; newspaper N; journal J; patent document P; compilation G; Ancient books O; Technical standards S; Dissertations D; Scientific and technological reports R; Reference tools K; Search tools W; Archives B; Audio tapes A;

Charts Q; Records L; Product samples X; Video tapes V ;Proceedings of the conference C;Chinese translation T;Music score I;Film Y;Manuscript H;Microfilm U;Slide Z;Microfilm F;OthersE.

Extended information:

References are coded consecutively with Arabic numerals according to the order in which they appear in the text, and the serial numbers are placed in square brackets. A document that is cited repeatedly is marked with the same serial number in the text.

Generally speaking, the page number (or page range) of the document cited once is listed in the references at the end of the text. The format is "Publishing Year" of the work or "Year, Volume (Issue)" of the journal, etc. ": Page number (or page number range)."

For documents cited multiple times, the page number or page number range of each reference (some publications also regard information that can indicate the location of cited documents as page numbers) is listed in the serial number of each reference. After the square brackets (only numbers are listed, without "p" or "page" and other surrounding words and characters; the connecting line in the middle of the page number range is a half-word line) and superscripted.