TJ Mechanical engineering and machinery 107 TK Electrical engineering. Electronics Nuclear engineering 82 TA Engineering (General). Civil engineering (General) 75 TP Chemical technology 68 L Education (General) 17 QD Chemistry 17 LB Theory and practice of education 14 QA75 Electronic computers. Computer science 14 T Technology (General) 8 TS Manufactures 8 Unspecified 8 QA Mathematics 7 QC Physics 7 Q Science (General) 5 TH Building construction 4 HD28 Management. Industrial Management 3 GV Recreation Leisure 2 LB2300 Higher Education 2 QA76 Computer software 2 QH Natural history 2 TC Hydraulic engineering. Ocean engineering 2 TD Environmental technology. Sanitary engineering 2 TL Motor vehicles. Aeronautics. Astronautics 2 TN Mining engineering. Metallurgy 2 G70.212-70.215 Geographic information system 1 GE Environmental Sciences 1 HD Industries. Land use. Labor 1 HE Transportation and Communications 1 HT101-395 Sociology, Urban 1 LB1603 Secondary Education. High schools 1