These 22 categories are: 1. Marxism-Leninism, Mao Zedong Thought and Deng Xiaoping Theory.
Philosophy, religion
Introduction to social science
Politics, law
E military
F economy
G. Culture, science, education and sports
H. Language and writing
I. Literature
J art
History, geography
Introduction to natural science
Mathematical science and chemistry
P astronomy, earth science
Q bioscience
Medicine and health
American agricultural science
technology
U transportation
V. Aviation and aerospace
X. Environmental Science and Safety Science
Z comprehensive books