Classification
330 - Economics
291
333 - Economics of land & energy
320 - Political science
229
363 - Other social problems & services
59
600 - Technology
40
380 - Commerce, communications & transportation
39
304 - Factors affecting social behavior
32
610 - Medicine & health
32
630 - Agriculture & related technologies
17
370 - Education
15
336 - Public finance
3