Classification
520 - Astronomy & allied sciences
146
530 - Physics
22
370 - Education
9
539 - Modern physics
7
551 - Geology, hydrology & meteorology
6
306 - Culture & institutions
5
500 - Natural sciences & mathematics
5
523 - Specific celestial bodies & phenomena
5
550 - Earth sciences
5
301 - Sociology & anthropology
3
526 - Mathematical geography
3
333 - Economics of land & energy
2
338 - Production
2
379 - Public policy issues in education
2
510 - Mathematics
2
576 - Genetics & evolution
2
629 - Other branches of engineering
2
170 - Ethics
1
305 - Social groups
1
320 - Political science
1
378 - Higher education
1
515 - Analysis
1
519 - Probabilities & applied mathematics
1
541 - Physical chemistry
1
572 - Biochemistry
1
621 - Applied physics
1