Classification
170 - Ethics
620 - Engineering & allied operations
900 - History & geography
600 - Technology
9
000 - Computer science, information & general works
6
333 - Economics of land & energy
6
700 - The arts; fine & decorative arts
6
140 - Specific philosophical schools
5
363 - Other social problems & services
5
610 - Medicine & health
5
720 - Architecture
5
320 - Political science
4
330 - Economics
4
340 - Law
4
380 - Commerce, communications & transportation
4
300 - Social sciences
3
551 - Geology, hydrology & meteorology
3
370 - Education
2
576 - Genetics & evolution
2
580 - Plants (Botany)
2
630 - Agriculture & related technologies
2
800 - Literature & rhetoric
2
361 - Social problems & social welfare in general
1
400 - Language
1
530 - Physics
1
581 - Specific topics in natural history
1