Classification
333 - Economics of land & energy
860
363 - Other social problems & services
330
577 - Ecology
326
551 - Geology, hydrology & meteorology
215
304 - Factors affecting social behavior
184
658 - General management
139
338 - Production
101
910 - Geography & travel
72
628 - Sanitary & municipal engineering
66
630 - Agriculture & related technologies
59
621 - Applied physics
51
330 - Economics
50
634 - Orchards, fruits & forestry
50
620 - Engineering & allied operations
48
550 - Earth sciences
46
631 - Techniques, equipment & materials
33
660 - Chemical engineering
33
320 - Political science
31
581 - Specific topics in natural history
30
613 - Personal health & safety
28
600 - Technology
27
700 - The arts; fine & decorative arts
26
670 - Manufacturing
25
900 - History & geography
21
344 - Labor, social, education & cultural law
20
572 - Biochemistry
20
624 - Civil engineering
20
580 - Plants (Botany)
19
571 - Physiology & related subjects
15
140 - Specific philosophical schools
12
300 - Social sciences
12
500 - Natural sciences & mathematics
12
614 - Incidence & prevention of disease
12
000 - Computer science, information & general works
11
307 - Communities
10
340 - Law
10
616 - Diseases
10
650 - Management & auxiliary services
10
174 - Occupational ethics
9
591 - Specific topics in natural history
9
720 - Architecture
9
380 - Commerce, communications & transportation
8
541 - Physical chemistry
8
570 - Life sciences; biology
8
579 - Microorganisms, fungi & algae
8
610 - Medicine & health
8
615 - Pharmacology & therapeutics
8
576 - Genetics & evolution
7
629 - Other branches of engineering
7
690 - Buildings
7
more ...