Classification
541 - Physical chemistry
1,418
620 - Engineering & allied operations
343
530 - Physics
283
543 - Analytical chemistry
156
547 - Organic chemistry
133
621 - Applied physics
128
546 - Inorganic chemistry
122
539 - Modern physics
109
660 - Chemical engineering
88
540 - Chemistry & allied sciences
73
536 - Heat
70
572 - Biochemistry
70
571 - Physiology & related subjects
50
551 - Geology, hydrology & meteorology
33
363 - Other social problems & services
32
333 - Economics of land & energy
30
548 - Crystallography
23
610 - Medicine & health
23
549 - Mineralogy
21
664 - Food technology
20
500 - Natural sciences & mathematics
19
000 - Computer science, information & general works
18
531 - Classical mechanics; solid mechanics
18
615 - Pharmacology & therapeutics
18
616 - Diseases
18
641 - Food & drink
17
537 - Electricity & electronics
16
577 - Ecology
12
700 - The arts; fine & decorative arts
9
520 - Astronomy & allied sciences
8
542 - Techniques, equipment & materials
8
670 - Manufacturing
8
538 - Magnetism
7
613 - Personal health & safety
7
519 - Probabilities & applied mathematics
6
534 - Sound & related vibrations
6
535 - Light & infrared & ultraviolet phenomena
5
628 - Sanitary & municipal engineering
5
570 - Life sciences; biology
4
576 - Genetics & evolution
4
580 - Plants (Botany)
4
600 - Technology
4
624 - Civil engineering
4
629 - Other branches of engineering
4
304 - Factors affecting social behavior
3
380 - Commerce, communications & transportation
3
501 - Philosophy & theory
3
523 - Specific celestial bodies & phenomena
3
630 - Agriculture & related technologies
3
631 - Techniques, equipment & materials
3
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