Classification
330 - Economics
651
610 - Medicine & health
211
333 - Economics of land & energy
144
304 - Factors affecting social behavior
99
363 - Other social problems & services
79
616 - Diseases
73
320 - Political science
71
370 - Education
56
306 - Culture & institutions
53
700 - The arts; fine & decorative arts
50
338 - Production
49
551 - Geology, hydrology & meteorology
48
658 - General management
47
000 - Computer science, information & general works
43
600 - Technology
37
577 - Ecology
36
380 - Commerce, communications & transportation
34
900 - History & geography
34
301 - Sociology & anthropology
33
620 - Engineering & allied operations
33
613 - Personal health & safety
32
614 - Incidence & prevention of disease
30
630 - Agriculture & related technologies
30
910 - Geography & travel
29
300 - Social sciences
28
305 - Social groups
27
140 - Specific philosophical schools
25
617 - Surgery & related medical specialties
22
100 - Philosophy & psychology
17
362 - Social welfare problems & services
17
361 - Social problems & social welfare in general
16
621 - Applied physics
16
570 - Life sciences; biology
14
571 - Physiology & related subjects
13
580 - Plants (Botany)
13
612 - Human physiology
13
634 - Orchards, fruits & forestry
13
006 - Special computer methods
12
331 - Labor economics
12
307 - Communities
11
500 - Natural sciences & mathematics
11
581 - Specific topics in natural history
11
340 - Law
10
371 - Schools & their activities; special education
10
629 - Other branches of engineering
10
004 - Data processing & computer science
9
576 - Genetics & evolution
9
615 - Pharmacology & therapeutics
9
150 - Psychology
8
327 - International relations
8
more ...