Classification
520 - Astronomy & allied sciences
553
500 - Natural sciences & mathematics
230
600 - Technology
122
523 - Specific celestial bodies & phenomena
114
530 - Physics
42
620 - Engineering & allied operations
23
621 - Applied physics
16
629 - Other branches of engineering
14
539 - Modern physics
12
000 - Computer science, information & general works
11
333 - Economics of land & energy
11
004 - Data processing & computer science
10
617 - Surgery & related medical specialties
9
001 - Knowledge
8
300 - Social sciences
8
576 - Genetics & evolution
8
610 - Medicine & health
8
700 - The arts; fine & decorative arts
8
330 - Economics
7
509 - Historical, geographic & persons treatment
7
770 - Photography, photographs & computer art
7
900 - History & geography
7
006 - Special computer methods
6
522 - Techniques, equipment & materials
6
658 - General management
6
005 - Computer programming, programs & data
5
320 - Political science
5
519 - Probabilities & applied mathematics
5
550 - Earth sciences
5
570 - Life sciences; biology
5
820 - English & Old English literatures
5
501 - Philosophy & theory
4
510 - Mathematics
4
515 - Analysis
4
535 - Light & infrared & ultraviolet phenomena
4
537 - Electricity & electronics
4
650 - Management & auxiliary services
4
681 - Precision instruments & other devices
4
910 - Geography & travel
4
302 - Social interaction
3
303 - Social processes
3
363 - Other social problems & services
3
616 - Diseases
3
680 - Manufacture for specific uses
3
771 - Techniques, equipment & materials
3
003 - Systems
2
011 - Bibliographies
2
020 - Library & information sciences
2
158 - Applied psychology
2
340 - Law
2
more ...