Classification
304 - Factors affecting social behavior
81
610 - Medicine & health
81
330 - Economics
66
320 - Political science
56
333 - Economics of land & energy
39
370 - Education
29
336 - Public finance
21
363 - Other social problems & services
21
600 - Technology
17
380 - Commerce, communications & transportation
10
630 - Agriculture & related technologies
4