Classification
140 - Specific philosophical schools
300 - Social sciences
320 - Political science
363 - Other social problems & services
600 - Technology
330 - Economics
2
333 - Economics of land & energy
2
581 - Specific topics in natural history
2
551 - Geology, hydrology & meteorology
1
620 - Engineering & allied operations
1
800 - Literature & rhetoric
1
900 - History & geography
1