Classification
307 - Communities
71
304 - Factors affecting social behavior
31
910 - Geography & travel
22
551 - Geology, hydrology & meteorology
4
710 - Civic & landscape art
4
696 - Utilities
3
720 - Architecture
3
320 - Political science
2
333 - Economics of land & energy
2
363 - Other social problems & services
2
330 - Economics
1
344 - Labor, social, education & cultural law
1
500 - Natural sciences & mathematics
1
550 - Earth sciences
1
629 - Other branches of engineering
1
700 - The arts; fine & decorative arts
1
740 - Drawing & decorative arts
1