Classification
330 - Economics
320 - Political science
428
333 - Economics of land & energy
291
600 - Technology
284
363 - Other social problems & services
164
380 - Commerce, communications & transportation
124
304 - Factors affecting social behavior
76
610 - Medicine & health
76
336 - Public finance
45
630 - Agriculture & related technologies
43
370 - Education
36