Classification
330 - Economics
678
333 - Economics of land & energy
383
320 - Political science
217
304 - Factors affecting social behavior
213
363 - Other social problems & services
152
630 - Agriculture & related technologies
119
610 - Medicine & health
107
338 - Production
82
551 - Geology, hydrology & meteorology
74
700 - The arts; fine & decorative arts
74
600 - Technology
62
000 - Computer science, information & general works
59
306 - Culture & institutions
57
370 - Education
52
900 - History & geography
52
380 - Commerce, communications & transportation
50
301 - Sociology & anthropology
49
577 - Ecology
45
658 - General management
44
300 - Social sciences
38
620 - Engineering & allied operations
38
305 - Social groups
34
580 - Plants (Botany)
34
910 - Geography & travel
32
140 - Specific philosophical schools
30
307 - Communities
29
004 - Data processing & computer science
27
581 - Specific topics in natural history
25
613 - Personal health & safety
24
331 - Labor economics
21
005 - Computer programming, programs & data
20
621 - Applied physics
20
614 - Incidence & prevention of disease
17
361 - Social problems & social welfare in general
16
006 - Special computer methods
14
340 - Law
14
003 - Systems
13
576 - Genetics & evolution
13
616 - Diseases
13
570 - Life sciences; biology
12
500 - Natural sciences & mathematics
11
302 - Social interaction
10
571 - Physiology & related subjects
10
628 - Sanitary & municipal engineering
10
550 - Earth sciences
9
720 - Architecture
9
170 - Ethics
8
200 - Religion
8
371 - Schools & their activities; special education
8
379 - Public policy issues in education
8
more ...