For the classification number and UDC list of China Library in various disciplines, see: the classification number and UDC list of China Library in various disciplines. Docx on the network. (Note: There is generally a charge for downloading the full text. Because of this version, I haven't figured out the source, and I haven't found an open link. I'm just promoting it.
When inquiring, the first thing that comes to mind is to use the dissertation database and the online public catalog inquiry system of the National Library, but the results are not satisfactory.
In the upper left corner of the dissertations of Wan Fang Data Knowledge Service System, there are China Library Classification Number and UDC Classification Number, but only a few of them are filled in, some are missing and some are wrong. Most dissertations on China Knowledge Network have no information about the classification number and UDC classification number of China Library. None of them provide a method to retrieve UDC classification number. There is no retrieval method of UDC classification number in the online public catalog query system of the National Library, and UDC classification number is not considered in the field name format data.
Secondly, if there are students from the previous session who are close to the subject direction, it is recommended to refer to them. If there is any further doubt, it will be further verified. If not, you can start from the first step. As for the classification number, there seems to be no hard and fast requirement. It is suggested that the classification number can be accurately filled in, and those that cannot be accurately corresponding can be vague.