Classification
900 - History & geography
38
370 - Education
25
300 - Social sciences
18
320 - Political science
18
700 - The arts; fine & decorative arts
17
330 - Economics
12
363 - Other social problems & services
9
600 - Technology
8
610 - Medicine & health
8
340 - Law
7
800 - Literature & rhetoric
7
000 - Computer science, information & general works
5
100 - Philosophy & psychology
5
333 - Economics of land & energy
5
380 - Commerce, communications & transportation
5
400 - Language
5
410 - Linguistics
5
720 - Architecture
5
140 - Specific philosophical schools
4
301 - Sociology & anthropology
4
304 - Factors affecting social behavior
4
576 - Genetics & evolution
4
361 - Social problems & social welfare in general
3
630 - Agriculture & related technologies
3
850 - Italian, Romanian & related literatures
3
360 - Social problems & services; associations
2
820 - English & Old English literatures
2
940 - History of Europe
2
321 - Systems of governments & states
1
398 - Folklore
1
450 - Italian, Romanian & related languages
1
520 - Astronomy & allied sciences
1
530 - Physics
1
616 - Diseases
1
620 - Engineering & allied operations
1
658 - General management
1
860 - Spanish & Portuguese literatures
1