Classification
581 - Specific topics in natural history
180
580 - Plants (Botany)
131
577 - Ecology
87
571 - Physiology & related subjects
86
333 - Economics of land & energy
53
630 - Agriculture & related technologies
32
634 - Orchards, fruits & forestry
26
578 - Natural history of organisms
21
660 - Chemical engineering
19
572 - Biochemistry
15
631 - Techniques, equipment & materials
13
363 - Other social problems & services
11
570 - Life sciences; biology
7
579 - Microorganisms, fungi & algae
6
576 - Genetics & evolution
4
910 - Geography & travel
4
551 - Geology, hydrology & meteorology
3
591 - Specific topics in natural history
3
592 - Invertebrates
3
664 - Food technology
3
900 - History & geography
3
304 - Factors affecting social behavior
2
550 - Earth sciences
2
615 - Pharmacology & therapeutics
2
000 - Computer science, information & general works
1
330 - Economics
1
343 - Military, tax, trade & industrial law
1
595 - Arthropods
1
600 - Technology
1
610 - Medicine & health
1
628 - Sanitary & municipal engineering
1
641 - Food & drink
1
690 - Buildings
1
720 - Architecture
1