Classification
330 - Economics
643
610 - Medicine & health
208
333 - Economics of land & energy
139
304 - Factors affecting social behavior
97
363 - Other social problems & services
76
616 - Diseases
73
320 - Political science
66
370 - Education
55
338 - Production
53
306 - Culture & institutions
51
551 - Geology, hydrology & meteorology
49
658 - General management
47
700 - The arts; fine & decorative arts
46
000 - Computer science, information & general works
41
577 - Ecology
36
600 - Technology
35
380 - Commerce, communications & transportation
34
620 - Engineering & allied operations
33
613 - Personal health & safety
31
614 - Incidence & prevention of disease
30
301 - Sociology & anthropology
29
630 - Agriculture & related technologies
29
140 - Specific philosophical schools
28
910 - Geography & travel
28
305 - Social groups
27
900 - History & geography
27
300 - Social sciences
22
617 - Surgery & related medical specialties
21
621 - Applied physics
16
361 - Social problems & social welfare in general
15
362 - Social welfare problems & services
15
100 - Philosophy & psychology
14
570 - Life sciences; biology
14
571 - Physiology & related subjects
13
612 - Human physiology
13
006 - Special computer methods
12
331 - Labor economics
12
580 - Plants (Botany)
12
634 - Orchards, fruits & forestry
12
307 - Communities
11
500 - Natural sciences & mathematics
11
340 - Law
10
371 - Schools & their activities; special education
10
581 - Specific topics in natural history
10
629 - Other branches of engineering
10
004 - Data processing & computer science
9
530 - Physics
9
576 - Genetics & evolution
9
615 - Pharmacology & therapeutics
9
150 - Psychology
8
more ...