Classification
507 - Education, research & related topics
253
370 - Education
105
530 - Physics
36
500 - Natural sciences & mathematics
32
540 - Chemistry & allied sciences
31
371 - Schools & their activities; special education
26
333 - Economics of land & energy
23
510 - Mathematics
21
620 - Engineering & allied operations
20
621 - Applied physics
15
304 - Factors affecting social behavior
14
330 - Economics
13
610 - Medicine & health
13
378 - Higher education
12
600 - Technology
12
700 - The arts; fine & decorative arts
12
300 - Social sciences
11
303 - Social processes
11
363 - Other social problems & services
11
551 - Geology, hydrology & meteorology
9
570 - Life sciences; biology
9
000 - Computer science, information & general works
8
900 - History & geography
8
910 - Geography & travel
8
100 - Philosophy & psychology
7
140 - Specific philosophical schools
7
400 - Language
7
520 - Astronomy & allied sciences
7
531 - Classical mechanics; solid mechanics
7
650 - Management & auxiliary services
7
306 - Culture & institutions
6
320 - Political science
6
006 - Special computer methods
5
380 - Commerce, communications & transportation
5
501 - Philosophy & theory
5
612 - Human physiology
5
660 - Chemical engineering
5
001 - Knowledge
4
003 - Systems
4
004 - Data processing & computer science
4
541 - Physical chemistry
4
572 - Biochemistry
4
576 - Genetics & evolution
4
580 - Plants (Botany)
4
302 - Social interaction
3
512 - Algebra
3
515 - Analysis
3
547 - Organic chemistry
3
577 - Ecology
3
607 - Education, research & related topics
3
more ...