Agriculture	89
Animal husbandry	1
Armored vehicles	1
Astronautics	1
Automated equipment	35
Automobiles	57
Aviation	12
Aviation medicine	1
Cables and cable production	5
Chemistry	140
Climatology	2
Coal	30
Commerce	2
Communications	11
Computer numerical control	2
Construction	13
Criminal law	1
Demography	2
Drilling	47
Dyalysis	4
Earth sciences	308
Economics	6
Education	2
Electric motors	4
Electric traction	4
Electricity	1
Electricity generation	1
Electrochemistry	1
Electronics	125
Energy industry	22
Engines	2
Environment	24
Finances	9
Fish farming pisciculture	1
Fishery fishing industry	1
Food industry	17
Forestry	13
General	117
Genetics	1
Geology	3
Health care	34
Hobbies and pastimes	2
Human rights activism	1
Immigration and citizenship	2
Industry	69
Information technology	54
International Monetary Fund	7
Isolation	2
Labor law	13
Laboratory equipment	2
Lasers	3
Law	2
Life sciences	100
Lighting other than cinema	4
Loading equipment	22
Marketing	2
Materials science	48
Measuring instruments	89
Mechanic engineering	276
Mechanics	2
Medical	221
Metallurgy	113
Meteorology	88
Mexican	8
Microsoft	8
Military	5
Municipal planning	2
Natural sciences	42
Nautical	1
Nuclear and fusion power	12
Nuclear physics	13
Obsolete / dated	2
Oil / petroleum	8
Ophthalmology	2
Packaging	51
Patents	3
Pest control	9
Physical sciences	23
Physics	9
Plastics	1
Politics	9
Power lines	1
Pulp and paper industry	2
Rail transport	2
Scientific	1
Scuba diving	7
Social science	3
Soil science	1
Spanish	7
Taxes	2
Technology	292
Textile industry	18
Thermal Energy	2
Transport	220
Ultrasound	6
Water resources	22
Wood processing	2