TP Chemical technology 194 TA Engineering (General). Civil engineering (General) 96 TJ Mechanical engineering and machinery 70 QD Chemistry 61 QC Physics 60 TK Electrical engineering. Electronics Nuclear engineering 24 Q Science (General) 22 T Technology (General) 17 QA75 Electronic computers. Computer science 14 HD28 Management. Industrial Management 9 QH Natural history 9 TH Building construction 8 Unspecified 8 QA Mathematics 7 NA Architecture 4 QH301 Biology 4 TD Environmental technology. Sanitary engineering 4 TS Manufactures 4 HT101-395 Sociology, Urban 3 R Medicine (General) 3 TC Hydraulic engineering. Ocean engineering 3 GE Environmental Sciences 2 HD Industries. Land use. Labor 2 HF Commerce 2 QE Geology 2 QP Physiology 2 SB Plant culture 2 G70.39-70.6 Remote sensing 1 GB Physical geography 1 H Social Sciences (General) 1