TK Electrical engineering. Electronics Nuclear engineering 400 TA Engineering (General). Civil engineering (General) 351 TJ Mechanical engineering and machinery 254 QA75 Electronic computers. Computer science 40 TD Environmental technology. Sanitary engineering 35 TS Manufactures 32 QA76 Computer software 30 TP Chemical technology 24 HD28 Management. Industrial Management 21 T Technology (General) 18 TK7885-7895 Computer engineer. Computer hardware 18 TH Building construction 15 HD Industries. Land use. Labor 9 HE Transportation and Communications 9 TC Hydraulic engineering. Ocean engineering 9 TE Highway engineering. Roads and pavements 9 QA Mathematics 8 Q Science (General) 7 GE Environmental Sciences 6 LB Theory and practice of education 6 Unspecified 6 L Education (General) 5 QE Geology 5 VM Naval architecture. Shipbuilding. Marine engineering 5 G70.212-70.215 Geographic information system 4 QD Chemistry 4 TG Bridge engineering 4 TL Motor vehicles. Aeronautics. Astronautics 4 TH434-437 Quantity surveying 3 TN Mining engineering. Metallurgy 3