Classification
630 - Agriculture & related technologies
539
330 - Economics
270
363 - Other social problems & services
143
333 - Economics of land & energy
91
380 - Commerce, communications & transportation
58
320 - Political science
53
600 - Technology
32
610 - Medicine & health
24
304 - Factors affecting social behavior
23
336 - Public finance
6
370 - Education
6
581 - Specific topics in natural history
3
340 - Law
2
700 - The arts; fine & decorative arts
2
100 - Philosophy & psychology
1
550 - Earth sciences
1
551 - Geology, hydrology & meteorology
1
576 - Genetics & evolution
1
620 - Engineering & allied operations
1
720 - Architecture
1
900 - History & geography
1