Journal articles?
Essays
According to GB3469-83 File Type and File Carrier Code, it is identified by a single letter.
Content expansion:
What is the description format of references?
1, author of the journal. Title [J] Title, year of publication, volume (issue): page number?
2. Monograph author. Title [m]. Version (first edition not recorded). Place of publication: publishing house, year of publication: page number?
3. Author, Title [c], Editor, Collection Name, Place of Publication: Press, Year of Publication: Start Page?
4. Author of the paper. Title [D] Save the location. Save unit. Year?
5. Title of the patent document [P]. Country. Types of patent documents. Patent number. Date of publication?
6. Standard number. Standard name?
7. newspaper author. Title. Newspaper name. Publication date (version)?
8. Author of the report. Title [R]. Save the location. Year?
9. Author of electronic document. Title [Identification of electronic documents and carrier types]. The source and date of the document.