Classification
577 - Ecology
65
551 - Geology, hydrology & meteorology
55
540 - Chemistry & allied sciences
20
363 - Other social problems & services
16
550 - Earth sciences
14
578 - Natural history of organisms
13
910 - Geography & travel
13
333 - Economics of land & energy
12
579 - Microorganisms, fungi & algae
10
581 - Specific topics in natural history
10
000 - Computer science, information & general works
7
500 - Natural sciences & mathematics
7
700 - The arts; fine & decorative arts
7
576 - Genetics & evolution
6
630 - Agriculture & related technologies
6
571 - Physiology & related subjects
5
572 - Biochemistry
5
628 - Sanitary & municipal engineering
5
330 - Economics
4
570 - Life sciences; biology
4
600 - Technology
4
616 - Diseases
4
631 - Techniques, equipment & materials
4
660 - Chemical engineering
4
340 - Law
3
574 - [Unassigned]
3
620 - Engineering & allied operations
3
140 - Specific philosophical schools
2
300 - Social sciences
2
304 - Factors affecting social behavior
2
380 - Commerce, communications & transportation
2
549 - Mineralogy
2
553 - Economic geology
2
560 - Paleontology; paleozoology
2
580 - Plants (Botany)
2
591 - Specific topics in natural history
2
900 - History & geography
2
001 - Knowledge
1
301 - Sociology & anthropology
1
320 - Political science
1
338 - Production
1
361 - Social problems & social welfare in general
1
414 - Phonology & phonetics
1
515 - Analysis
1
541 - Physical chemistry
1
543 - Analytical chemistry
1
547 - Organic chemistry
1
610 - Medicine & health
1
612 - Human physiology
1
613 - Personal health & safety
1
more ...