Classification
330 - Economics
24
370 - Education
24
658 - General management
19
900 - History & geography
14
000 - Computer science, information & general works
13
300 - Social sciences
13
363 - Other social problems & services
13
320 - Political science
12
600 - Technology
12
616 - Diseases
11
700 - The arts; fine & decorative arts
9
340 - Law
8
720 - Architecture
8
140 - Specific philosophical schools
7
333 - Economics of land & energy
4
551 - Geology, hydrology & meteorology
4
650 - Management & auxiliary services
4
301 - Sociology & anthropology
3
304 - Factors affecting social behavior
3
331 - Labor economics
3
338 - Production
3
380 - Commerce, communications & transportation
3
004 - Data processing & computer science
2
519 - Probabilities & applied mathematics
2
610 - Medicine & health
2
620 - Engineering & allied operations
2
629 - Other branches of engineering
2
657 - Accounting
2
001 - Knowledge
1
003 - Systems
1
005 - Computer programming, programs & data
1
006 - Special computer methods
1
150 - Psychology
1
160 - Logic
1
170 - Ethics
1
200 - Religion
1
302 - Social interaction
1
339 - Macroeconomics & related topics
1
351 - Public administration
1
355 - Military science
1
371 - Schools & their activities; special education
1
400 - Language
1
410 - Linguistics
1
500 - Natural sciences & mathematics
1
510 - Mathematics
1
511 - General principles of mathematics
1
520 - Astronomy & allied sciences
1
540 - Chemistry & allied sciences
1
613 - Personal health & safety
1
614 - Incidence & prevention of disease
1
more ...