Classification
620 - Engineering & allied operations
169
602 - Miscellany
115
690 - Buildings
83
624 - Civil engineering
76
671 - Metalworking & primary metal products
75
621 - Applied physics
41
658 - General management
37
697 - Heating, ventilating & air-conditioning
36
669 - Metallurgy
24
696 - Utilities
24
681 - Precision instruments & other devices
20
670 - Manufacturing
19
665 - Industrial oils, fats, waxes & gases
15
660 - Chemical engineering
14
600 - Technology
12
693 - Specific materials & purposes
11
000 - Computer science, information & general works
10
005 - Computer programming, programs & data
10
340 - Law
8
540 - Chemistry & allied sciences
8
628 - Sanitary & municipal engineering
8
530 - Physics
6
629 - Other branches of engineering
6
536 - Heat
5
625 - Engineering of railroads & roads
5
674 - Lumber processing, wood products & cork
5
363 - Other social problems & services
4
610 - Medicine & health
4
650 - Management & auxiliary services
4
651 - Office services
4
720 - Architecture
4
352 - General considerations of public administration
3
539 - Modern physics
3
613 - Personal health & safety
3
664 - Food technology
3
020 - Library & information sciences
2
344 - Labor, social, education & cultural law
2
510 - Mathematics
2
531 - Classical mechanics; solid mechanics
2
535 - Light & infrared & ultraviolet phenomena
2
543 - Analytical chemistry
2
627 - Hydraulic engineering
2
652 - Processes of written communication
2
677 - Textiles
2
688 - Other final products & packaging
2
692 - Auxiliary construction practices
2
001 - Knowledge
1
004 - Data processing & computer science
1
025 - Library operations
1
333 - Economics of land & energy
1
more ...