Classification
170 - Ethics
330 - Economics
900 - History & geography
320 - Political science
25
100 - Philosophy & psychology
7
333 - Economics of land & energy
7
600 - Technology
7
700 - The arts; fine & decorative arts
7
300 - Social sciences
6
370 - Education
6
000 - Computer science, information & general works
5
140 - Specific philosophical schools
5
340 - Law
5
620 - Engineering & allied operations
5
363 - Other social problems & services
3
581 - Specific topics in natural history
3
610 - Medicine & health
3
301 - Sociology & anthropology
2
304 - Factors affecting social behavior
2
380 - Commerce, communications & transportation
2
551 - Geology, hydrology & meteorology
2
720 - Architecture
2
800 - Literature & rhetoric
2
160 - Logic
1
400 - Language
1
530 - Physics
1
576 - Genetics & evolution
1
658 - General management
1