Classification
500 - Natural sciences & mathematics
101
621 - Applied physics
28
510 - Mathematics
25
530 - Physics
22
519 - Probabilities & applied mathematics
20
629 - Other branches of engineering
19
620 - Engineering & allied operations
15
551 - Geology, hydrology & meteorology
13
616 - Diseases
12
520 - Astronomy & allied sciences
11
306 - Culture & institutions
10
509 - Historical, geographic & persons treatment
10
320 - Political science
9
641 - Food & drink
9
664 - Food technology
9
515 - Analysis
8
516 - Geometry
8
658 - General management
8
004 - Data processing & computer science
7
330 - Economics
7
531 - Classical mechanics; solid mechanics
7
539 - Modern physics
7
900 - History & geography
7
650 - Management & auxiliary services
6
301 - Sociology & anthropology
5
302 - Social interaction
5
570 - Life sciences; biology
5
005 - Computer programming, programs & data
4
150 - Psychology
4
333 - Economics of land & energy
4
340 - Law
4
361 - Social problems & social welfare in general
4
540 - Chemistry & allied sciences
4
370 - Education
3
378 - Higher education
3
501 - Philosophy & theory
3
547 - Organic chemistry
3
572 - Biochemistry
3
579 - Microorganisms, fungi & algae
3
610 - Medicine & health
3
630 - Agriculture & related technologies
3
660 - Chemical engineering
3
670 - Manufacturing
3
006 - Special computer methods
2
155 - Differential & developmental psychology
2
332 - Financial economics
2
343 - Military, tax, trade & industrial law
2
507 - Education, research & related topics
2
512 - Algebra
2
523 - Specific celestial bodies & phenomena
2
more ...