Classification
551 - Geology, hydrology & meteorology
1,226
330 - Economics
1,005
333 - Economics of land & energy
758
363 - Other social problems & services
701
700 - The arts; fine & decorative arts
349
000 - Computer science, information & general works
341
600 - Technology
288
320 - Political science
282
620 - Engineering & allied operations
228
577 - Ecology
213
900 - History & geography
195
630 - Agriculture & related technologies
187
304 - Factors affecting social behavior
180
610 - Medicine & health
180
580 - Plants (Botany)
175
380 - Commerce, communications & transportation
157
581 - Specific topics in natural history
156
140 - Specific philosophical schools
155
910 - Geography & travel
111
550 - Earth sciences
109
500 - Natural sciences & mathematics
91
370 - Education
78
300 - Social sciences
72
576 - Genetics & evolution
71
621 - Applied physics
70
338 - Production
69
720 - Architecture
69
340 - Law
65
414 - Phonology & phonetics
53
658 - General management
47
530 - Physics
43
100 - Philosophy & psychology
39
540 - Chemistry & allied sciences
38
344 - Labor, social, education & cultural law
35
800 - Literature & rhetoric
32
170 - Ethics
22
612 - Human physiology
22
628 - Sanitary & municipal engineering
18
660 - Chemical engineering
18
301 - Sociology & anthropology
17
631 - Techniques, equipment & materials
17
200 - Religion
15
307 - Communities
15
624 - Civil engineering
15
400 - Language
14
571 - Physiology & related subjects
14
341 - Law of nations
11
578 - Natural history of organisms
11
361 - Social problems & social welfare in general
10
613 - Personal health & safety
10
more ...