Classification Query of China Library Classification
The basic categories are five: Marxism-Leninism, Mao Zedong and Deng Xiaoping; Philosophy and religion; Social science; Natural science; Comprehensive books.
* * * Twenty-two categories, each with one letter. Do not use the letters l, m, w and y.
The Ministry of Natural Science includes the twelfth to twenty-first basic categories (* * * 10) expressed by letters: N, O, P, Q, R, S, T, U, V, X.
The following are all the basic categories of the Ministry of Natural Science, in order of serial number, letter and name:
12 N introduction to natural science
13 O mathematical science and chemical mathematics, mechanics, physics, chemistry, crystallography
14 P astronomy, earth science astronomy, surveying, geophysics, atmospheric science (meteorology), geology, oceanography, physical geography.
15 Q one of the biological sciences? Second: Zoology? Third: entomology? Fourth: Anthropology
16 R one of medical and health care? Second: basic medicine
17 S agricultural science
18 T industrial technology
19 U transportation
20 V aviation and aerospace
2 1 X environmental science and safety science