Subject
Refrigeration and refrigerating machinery
75
Air conditioning
58
Heating
19
Ventilation
11
Maintenance and repair
9
Electrical engineering
6
Equipment and supplies
5
Air Conditioning
3
Electric engineering
3
Electric equipment
3
Elektrik equipment
3
Eletric equipment
3
Refrigeration And Refrigerating Machinery
3
Refrigeration and refrigeration machinery
3
Air Conditioning-Electric equipment
2
Air conditioning industry
2
Engineering
2
Heating and ventilation industry
2
Refrigeration
2
Refrigeration and refrigerating machinery-Electric equipment
2
Vocational guidance
2
Handbooks, manuals, etc
1
Study and teaching (Secondary)
1