Classification
333 - Economics of land & energy
56
304 - Factors affecting social behavior
33
363 - Other social problems & services
32
370 - Education
31
003 - Systems
12
700 - The arts; fine & decorative arts
11
330 - Economics
9
551 - Geology, hydrology & meteorology
9
006 - Special computer methods
7
507 - Education, research & related topics
7
577 - Ecology
7
600 - Technology
7
610 - Medicine & health
7
320 - Political science
6
338 - Production
6
380 - Commerce, communications & transportation
6
500 - Natural sciences & mathematics
6
620 - Engineering & allied operations
6
658 - General management
6
900 - History & geography
6
371 - Schools & their activities; special education
5
000 - Computer science, information & general works
4
100 - Philosophy & psychology
4
547 - Organic chemistry
4
581 - Specific topics in natural history
4
621 - Applied physics
4
628 - Sanitary & municipal engineering
4
910 - Geography & travel
4
140 - Specific philosophical schools
3
378 - Higher education
3
660 - Chemical engineering
3
720 - Architecture
3
200 - Religion
2
300 - Social sciences
2
301 - Sociology & anthropology
2
303 - Social processes
2
372 - Elementary education
2
570 - Life sciences; biology
2
576 - Genetics & evolution
2
624 - Civil engineering
2
630 - Agriculture & related technologies
2
800 - Literature & rhetoric
2
036 - Encyclopedias in Spanish & Portuguese
1
113 - Cosmology
1
155 - Differential & developmental psychology
1
170 - Ethics
1
201 - Religious mythology & social theology
1
297 - Islam, Babism & Bahai Faith
1
306 - Culture & institutions
1
331 - Labor economics
1
more ...