Classification
330 - Economics
621
320 - Political science
237
333 - Economics of land & energy
200
370 - Education
145
900 - History & geography
119
304 - Factors affecting social behavior
104
340 - Law
98
610 - Medicine & health
97
306 - Culture & institutions
90
658 - General management
87
363 - Other social problems & services
84
338 - Production
81
700 - The arts; fine & decorative arts
79
600 - Technology
67
300 - Social sciences
58
551 - Geology, hydrology & meteorology
53
380 - Commerce, communications & transportation
52
301 - Sociology & anthropology
51
140 - Specific philosophical schools
49
200 - Religion
48
577 - Ecology
48
000 - Computer science, information & general works
42
327 - International relations
40
336 - Public finance
38
616 - Diseases
36
305 - Social groups
33
005 - Computer programming, programs & data
31
630 - Agriculture & related technologies
31
004 - Data processing & computer science
30
371 - Schools & their activities; special education
30
620 - Engineering & allied operations
28
303 - Social processes
26
580 - Plants (Botany)
26
910 - Geography & travel
26
006 - Special computer methods
25
331 - Labor economics
25
307 - Communities
24
342 - Constitutional & administrative law
24
302 - Social interaction
23
378 - Higher education
23
400 - Language
23
100 - Philosophy & psychology
21
364 - Criminology
19
530 - Physics
19
341 - Law of nations
18
361 - Social problems & social welfare in general
18
500 - Natural sciences & mathematics
18
621 - Applied physics
18
155 - Differential & developmental psychology
17
613 - Personal health & safety
17
more ...