Classification
620 - Engineering & allied operations
600 - Technology
13
630 - Agriculture & related technologies
11
900 - History & geography
4
363 - Other social problems & services
3
320 - Political science
2
330 - Economics
1
333 - Economics of land & energy
1
500 - Natural sciences & mathematics
1
520 - Astronomy & allied sciences
1
581 - Specific topics in natural history
1