Classification
577 - Ecology
241
333 - Economics of land & energy
72
570 - Life sciences; biology
30
581 - Specific topics in natural history
27
630 - Agriculture & related technologies
18
910 - Geography & travel
17
580 - Plants (Botany)
16
616 - Diseases
16
571 - Physiology & related subjects
12
301 - Sociology & anthropology
11
363 - Other social problems & services
11
550 - Earth sciences
10
579 - Microorganisms, fungi & algae
10
551 - Geology, hydrology & meteorology
7
591 - Specific topics in natural history
7
001 - Knowledge
6
300 - Social sciences
6
330 - Economics
6
572 - Biochemistry
6
634 - Orchards, fruits & forestry
6
338 - Production
5
500 - Natural sciences & mathematics
5
590 - Animals (Zoology)
4
599 - Mammals
4
658 - General management
4
304 - Factors affecting social behavior
3
519 - Probabilities & applied mathematics
3
578 - Natural history of organisms
3
660 - Chemical engineering
3
612 - Human physiology
2
628 - Sanitary & municipal engineering
2
639 - Hunting, fishing & conservation
2
003 - Systems
1
155 - Differential & developmental psychology
1
158 - Applied psychology
1
306 - Culture & institutions
1
370 - Education
1
573 - Specific physiological systems in animals
1
576 - Genetics & evolution
1
592 - Invertebrates
1
600 - Technology
1
613 - Personal health & safety
1
614 - Incidence & prevention of disease
1
620 - Engineering & allied operations
1
621 - Applied physics
1
624 - Civil engineering
1
631 - Techniques, equipment & materials
1
636 - Animal husbandry
1
641 - Food & drink
1
664 - Food technology
1
more ...