Classification
500 - Natural sciences & mathematics
83
621 - Applied physics
26
620 - Engineering & allied operations
19
519 - Probabilities & applied mathematics
18
516 - Geometry
11
510 - Mathematics
10
530 - Physics
10
320 - Political science
9
629 - Other branches of engineering
9
551 - Geology, hydrology & meteorology
8
616 - Diseases
8
515 - Analysis
7
650 - Management & auxiliary services
7
900 - History & geography
7
531 - Classical mechanics; solid mechanics
6
658 - General management
6
004 - Data processing & computer science
5
301 - Sociology & anthropology
5
539 - Modern physics
5
641 - Food & drink
5
664 - Food technology
5
150 - Psychology
4
330 - Economics
4
610 - Medicine & health
4
340 - Law
3
378 - Higher education
3
509 - Historical, geographic & persons treatment
3
541 - Physical chemistry
3
570 - Life sciences; biology
3
660 - Chemical engineering
3
670 - Manufacturing
3
000 - Computer science, information & general works
2
006 - Special computer methods
2
342 - Constitutional & administrative law
2
343 - Military, tax, trade & industrial law
2
361 - Social problems & social welfare in general
2
370 - Education
2
371 - Schools & their activities; special education
2
400 - Language
2
523 - Specific celestial bodies & phenomena
2
540 - Chemistry & allied sciences
2
572 - Biochemistry
2
617 - Surgery & related medical specialties
2
690 - Buildings
2
001 - Knowledge
1
005 - Computer programming, programs & data
1
100 - Philosophy & psychology
1
120 - Epistemology, causation & humankind
1
304 - Factors affecting social behavior
1
306 - Culture & institutions
1
more ...