Classification
634 - Orchards, fruits & forestry
470
577 - Ecology
386
630 - Agriculture & related technologies
313
330 - Economics
191
580 - Plants (Botany)
165
320 - Political science
149
333 - Economics of land & energy
125
581 - Specific topics in natural history
61
571 - Physiology & related subjects
58
363 - Other social problems & services
55
340 - Law
41
551 - Geology, hydrology & meteorology
38
000 - Computer science, information & general works
37
660 - Chemical engineering
35
700 - The arts; fine & decorative arts
31
631 - Techniques, equipment & materials
28
579 - Microorganisms, fungi & algae
25
620 - Engineering & allied operations
25
910 - Geography & travel
24
600 - Technology
22
610 - Medicine & health
18
304 - Factors affecting social behavior
16
572 - Biochemistry
15
900 - History & geography
15
550 - Earth sciences
13
300 - Social sciences
12
344 - Labor, social, education & cultural law
12
380 - Commerce, communications & transportation
12
616 - Diseases
12
140 - Specific philosophical schools
9
578 - Natural history of organisms
9
664 - Food technology
9
590 - Animals (Zoology)
8
621 - Applied physics
8
641 - Food & drink
8
338 - Production
7
576 - Genetics & evolution
7
800 - Literature & rhetoric
7
500 - Natural sciences & mathematics
6
519 - Probabilities & applied mathematics
6
570 - Life sciences; biology
6
612 - Human physiology
6
624 - Civil engineering
6
301 - Sociology & anthropology
5
370 - Education
5
592 - Invertebrates
5
628 - Sanitary & municipal engineering
5
658 - General management
5
595 - Arthropods
4
614 - Incidence & prevention of disease
4
more ...