Classification
577 - Ecology
24
591 - Specific topics in natural history
10
333 - Economics of land & energy
6
590 - Animals (Zoology)
3
630 - Agriculture & related technologies
3
660 - Chemical engineering
3
338 - Production
2
578 - Natural history of organisms
2
581 - Specific topics in natural history
2
631 - Techniques, equipment & materials
2
634 - Orchards, fruits & forestry
2
551 - Geology, hydrology & meteorology
1
560 - Paleontology; paleozoology
1
571 - Physiology & related subjects
1
580 - Plants (Botany)
1
595 - Arthropods
1
615 - Pharmacology & therapeutics
1
621 - Applied physics
1
628 - Sanitary & municipal engineering
1
910 - Geography & travel
1
919 - Geography of & travel in other areas
1