TA Engineering (General). Civil engineering (General) 274 TD Environmental technology. Sanitary engineering 169 TJ Mechanical engineering and machinery 125 TK Electrical engineering. Electronics Nuclear engineering 108 TP Chemical technology 37 T Technology (General) 23 GE Environmental Sciences 20 TC Hydraulic engineering. Ocean engineering 9 HD28 Management. Industrial Management 8 TH Building construction 8 H Social Sciences (General) 5 HD Industries. Land use. Labor 5 L Education (General) 4 Q Science (General) 4 QA75 Electronic computers. Computer science 4 QA76 Computer software 4 TE Highway engineering. Roads and pavements 4 VM Naval architecture. Shipbuilding. Marine engineering 4 HE Transportation and Communications 3 QD Chemistry 3 TN Mining engineering. Metallurgy 3 GV Recreation Leisure 2 HT Communities. Classes. Races 2 K Law (General) 2 NA Architecture 2 QE Geology 2 T58.5-58.64 Information technology 2 TL Motor vehicles. Aeronautics. Astronautics 2 TS Manufactures 2 Unspecified 2