Classification
520 - Astronomy & allied sciences
96
530 - Physics
5
539 - Modern physics
2
510 - Mathematics
1
523 - Specific celestial bodies & phenomena
1
549 - Mineralogy
1
550 - Earth sciences
1
551 - Geology, hydrology & meteorology
1
621 - Applied physics
1
629 - Other branches of engineering
1
910 - Geography & travel
1