Classification
530 - Physics
23
539 - Modern physics
19
005 - Computer programming, programs & data
14
620 - Engineering & allied operations
14
006 - Special computer methods
12
621 - Applied physics
12
519 - Probabilities & applied mathematics
9
515 - Analysis
6
004 - Data processing & computer science
5
500 - Natural sciences & mathematics
5
541 - Physical chemistry
5
616 - Diseases
5
001 - Knowledge
4
300 - Social sciences
4
658 - General management
4
330 - Economics
3
518 - Numerical analysis
3
520 - Astronomy & allied sciences
3
551 - Geology, hydrology & meteorology
3
572 - Biochemistry
3
003 - Systems
2
333 - Economics of land & energy
2
368 - Insurance
2
510 - Mathematics
2
516 - Geometry
2
534 - Sound & related vibrations
2
540 - Chemistry & allied sciences
2
547 - Organic chemistry
2
571 - Physiology & related subjects
2
576 - Genetics & evolution
2
629 - Other branches of engineering
2
170 - Ethics
1
307 - Communities
1
331 - Labor economics
1
332 - Financial economics
1
371 - Schools & their activities; special education
1
381 - Commerce
1
512 - Algebra
1
514 - Topology
1
531 - Classical mechanics; solid mechanics
1
537 - Electricity & electronics
1
538 - Magnetism
1
543 - Analytical chemistry
1
546 - Inorganic chemistry
1
548 - Crystallography
1
573 - Specific physiological systems in animals
1
577 - Ecology
1
581 - Specific topics in natural history
1
595 - Arthropods
1
610 - Medicine & health
1
more ...