Classification
610 - Medicine & health
251
520 - Astronomy & allied sciences
221
150 - Psychology
180
530 - Physics
124
500 - Natural sciences & mathematics
116
510 - Mathematics
88
616 - Diseases
85
330 - Economics
66
600 - Technology
52
629 - Other branches of engineering
34
519 - Probabilities & applied mathematics
32
621 - Applied physics
32
306 - Culture & institutions
31
320 - Political science
26
370 - Education
24
650 - Management & auxiliary services
24
551 - Geology, hydrology & meteorology
22
158 - Applied psychology
19
620 - Engineering & allied operations
19
333 - Economics of land & energy
17
540 - Chemistry & allied sciences
17
615 - Pharmacology & therapeutics
17
617 - Surgery & related medical specialties
17
618 - Gynecology, obstetrics, pediatrics & geriatrics
16
658 - General management
16
900 - History & geography
16
155 - Differential & developmental psychology
12
509 - Historical, geographic & persons treatment
12
516 - Geometry
12
100 - Philosophy & psychology
11
302 - Social interaction
11
570 - Life sciences; biology
11
614 - Incidence & prevention of disease
11
305 - Social groups
10
613 - Personal health & safety
10
641 - Food & drink
10
664 - Food technology
10
332 - Financial economics
9
338 - Production
9
361 - Social problems & social welfare in general
9
304 - Factors affecting social behavior
8
523 - Specific celestial bodies & phenomena
8
301 - Sociology & anthropology
7
515 - Analysis
7
550 - Earth sciences
7
000 - Computer science, information & general works
6
004 - Data processing & computer science
6
531 - Classical mechanics; solid mechanics
6
539 - Modern physics
6
576 - Genetics & evolution
6
more ...