Classification
333 - Economics of land & energy
3
520 - Astronomy & allied sciences
580 - Plants (Botany)
3
610 - Medicine & health
330 - Economics
2
363 - Other social problems & services
2
551 - Geology, hydrology & meteorology
2
581 - Specific topics in natural history
2
630 - Agriculture & related technologies
2
000 - Computer science, information & general works
1
304 - Factors affecting social behavior
1
320 - Political science
1
600 - Technology
1
700 - The arts; fine & decorative arts
1