These five categories are Marxism-Leninism, Mao Zedong Thought, philosophy, social science, natural science and comprehensive books.

22 basic categories:

A: Marxism–Leninism, Mao Zedong Thought and Deng Xiaoping Theory.

Philosophy and religion

C: introduction to social science

D: politics, law

E: military

F: Economy class

G: culture, science, education and sports.

H: language, writing

I: literature

art

K: history, geography

N: introduction to natural science

Mathematical science and chemistry

Professor: astronomy, earth science

Q: Biological science.

Medicine and health

Study: agricultural science

T: industrial technology

U: transportation

V: Aviation and Aerospace

X: environmental science, labor protection science (safety science)

Z: comprehensive books