Subject
Transistors
7
Chemistry, Technical
4
Clothing and dress
4
Electronics
4
Electroplating
4
Food
4
Handicraft
4
Mechanical drawing
4
Mining engineering
4
Petroleum Geology
4
Technical writing
4
Uranium ores
4
Cinematography
3
Dressmaking
3
Electrical engineering
3
Geology
3
Hydraulic engineering
3
Metallurgy
3
Mines and mineral resources
3
Natural gas
3
Oil well logging
3
Ore deposits
3
Plastics
3
Prospecting
3
Space flight to the moon
3
Surveying
3
Table setting and decoration
3
Thorium
3
Aerodynamics
2
Aluminum
2
Astronautics
2
Beryllium
2
Ceramics
2
Chemical engineering
2
Chemistry
2
Color
2
Cooking
2
Cooking (Game)
2
Copper mines and mining
2
Drawing Study and teaching
2
Electronic instruments
2
Engineering
2
Engineering Study and teaching
2
Engineering mathematics
2
Geology, Economic
2
Gold mines and mining
2
Heat resistant alloys
2
Hydraulics
2
Irrigation
2
Jewelry
2
more ...