TK Electrical engineering. Electronics Nuclear engineering 14 TA Engineering (General). Civil engineering (General) 13 QA75 Electronic computers. Computer science 6 TP Chemical technology 5 HE Transportation and Communications 4 G70.212-70.215 Geographic information system 3 HD28 Management. Industrial Management 3 QA76 Computer software 3 TD Environmental technology. Sanitary engineering 3 TJ Mechanical engineering and machinery 2 VM Naval architecture. Shipbuilding. Marine engineering 2 GE Environmental Sciences 1 HD Industries. Land use. Labor 1 HD1394-1394.5 Real estate management 1 HF Commerce 1 HJ Public Finance 1 NA Architecture 1 NA9000-9284 City planning 1 T Technology (General) 1 TC Hydraulic engineering. Ocean engineering 1 TH Building construction 1 V Naval Science (General) 1