Classification
363 - Other social problems & services
3
600 - Technology
3
620 - Engineering & allied operations
3
900 - History & geography
333 - Economics of land & energy
2
380 - Commerce, communications & transportation
2
551 - Geology, hydrology & meteorology
2
700 - The arts; fine & decorative arts
2
330 - Economics
1
530 - Physics
1