Classification
900 - History & geography
600 - Technology
23
620 - Engineering & allied operations
9
140 - Specific philosophical schools
7
300 - Social sciences
6
100 - Philosophy & psychology
4
170 - Ethics
4
700 - The arts; fine & decorative arts
4
363 - Other social problems & services
3
720 - Architecture
3
000 - Computer science, information & general works
2
330 - Economics
2
333 - Economics of land & energy
2
380 - Commerce, communications & transportation
2
610 - Medicine & health
2
800 - Literature & rhetoric
2
630 - Agriculture & related technologies
1