At present, libraries in China all use the China Library Classification to classify books according to their subject attributes, and then give them corresponding classification codes (the first place is the combination of English letters and Arabic numerals).

Accordingly, the following categories will help you:

Story category (novel): I 24

Literature (literary theory): I 0

Popular Science: (Natural Science Education and Popularization) N4

Composition category: (writing) H 15

I hope the above reply can help you. Please accept it if you are satisfied.