Classification
140 - Specific philosophical schools
320 - Political science
333 - Economics of land & energy
2
380 - Commerce, communications & transportation
2
581 - Specific topics in natural history
600 - Technology
2
620 - Engineering & allied operations
900 - History & geography
2
330 - Economics
1
363 - Other social problems & services
1
700 - The arts; fine & decorative arts
1