Classification
333 - Economics of land & energy
27
304 - Factors affecting social behavior
17
170 - Ethics
14
100 - Philosophy & psychology
12
363 - Other social problems & services
11
577 - Ecology
11
320 - Political science
10
330 - Economics
8
003 - Systems
7
501 - Philosophy & theory
7
570 - Life sciences; biology
7
140 - Specific philosophical schools
6
142 - Critical philosophy
6
338 - Production
6
507 - Education, research & related topics
6
550 - Earth sciences
6
500 - Natural sciences & mathematics
5
700 - The arts; fine & decorative arts
5
800 - Literature & rhetoric
5
174 - Occupational ethics
4
300 - Social sciences
4
306 - Culture & institutions
4
344 - Labor, social, education & cultural law
4
551 - Geology, hydrology & meteorology
4
600 - Technology
4
629 - Other branches of engineering
4
900 - History & geography
4
006 - Special computer methods
3
111 - Ontology
3
200 - Religion
3
340 - Law
3
370 - Education
3
576 - Genetics & evolution
3
581 - Specific topics in natural history
3
612 - Human physiology
3
613 - Personal health & safety
3
650 - Management & auxiliary services
3
910 - Geography & travel
3
001 - Knowledge
2
004 - Data processing & computer science
2
113 - Cosmology
2
120 - Epistemology, causation & humankind
2
153 - Mental processes & intelligence
2
301 - Sociology & anthropology
2
303 - Social processes
2
400 - Language
2
580 - Plants (Botany)
2
620 - Engineering & allied operations
2
658 - General management
2
720 - Architecture
2
more ...