Classification
330 - Economics
581 - Specific topics in natural history
363 - Other social problems & services
15
333 - Economics of land & energy
14
320 - Political science
10
600 - Technology
6
140 - Specific philosophical schools
5
551 - Geology, hydrology & meteorology
5
700 - The arts; fine & decorative arts
4
340 - Law
3
580 - Plants (Botany)
3
630 - Agriculture & related technologies
3
100 - Philosophy & psychology
2
300 - Social sciences
2
610 - Medicine & health
2
170 - Ethics
1
200 - Religion
1
301 - Sociology & anthropology
1
304 - Factors affecting social behavior
1
380 - Commerce, communications & transportation
1
576 - Genetics & evolution
1
620 - Engineering & allied operations
1
900 - History & geography
1