Classification
100 - Philosophy & psychology
2
200 - Religion
2
000 - Computer science, information & general works
1
120 - Epistemology, causation & humankind
1
140 - Specific philosophical schools
1
333 - Economics of land & energy
1
363 - Other social problems & services
1
380 - Commerce, communications & transportation
1
520 - Astronomy & allied sciences
1
530 - Physics
1
900 - History & geography
1