Classification
304 - Factors affecting social behavior
300
577 - Ecology
62
306 - Culture & institutions
37
305 - Social groups
29
570 - Life sciences; biology
29
519 - Probabilities & applied mathematics
28
301 - Sociology & anthropology
26
330 - Economics
23
579 - Microorganisms, fungi & algae
23
571 - Physiology & related subjects
21
338 - Production
20
333 - Economics of land & energy
19
576 - Genetics & evolution
18
610 - Medicine & health
18
515 - Analysis
16
307 - Communities
13
331 - Labor economics
13
591 - Specific topics in natural history
12
614 - Incidence & prevention of disease
12
613 - Personal health & safety
11
300 - Social sciences
9
320 - Political science
9
616 - Diseases
9
658 - General management
9
361 - Social problems & social welfare in general
6
660 - Chemical engineering
5
910 - Geography & travel
5
302 - Social interaction
4
339 - Macroeconomics & related topics
4
530 - Physics
4
580 - Plants (Botany)
4
581 - Specific topics in natural history
4
004 - Data processing & computer science
3
150 - Psychology
3
340 - Law
3
362 - Social welfare problems & services
3
510 - Mathematics
3
572 - Biochemistry
3
592 - Invertebrates
3
303 - Social processes
2
343 - Military, tax, trade & industrial law
2
344 - Labor, social, education & cultural law
2
363 - Other social problems & services
2
370 - Education
2
551 - Geology, hydrology & meteorology
2
590 - Animals (Zoology)
2
618 - Gynecology, obstetrics, pediatrics & geriatrics
2
621 - Applied physics
2
634 - Orchards, fruits & forestry
2
636 - Animal husbandry
2
more ...