TP Chemical technology 369 TA Engineering (General). Civil engineering (General) 181 TJ Mechanical engineering and machinery 151 QD Chemistry 113 QC Physics 103 T Technology (General) 79 TK Electrical engineering. Electronics Nuclear engineering 65 Q Science (General) 53 QA75 Electronic computers. Computer science 21 QH Natural history 19 QA Mathematics 15 NA Architecture 12 HD28 Management. Industrial Management 11 QH301 Biology 11 TH Building construction 11 Unspecified 9 Q Science 8 TS Manufactures 8 TD Environmental technology. Sanitary engineering 7 R Medicine (General) 5 GE Environmental Sciences 4 HT101-395 Sociology, Urban 4 L Education (General) 4 H Social Sciences (General) 3 HD Industries. Land use. Labor 3 HF Commerce 3 QA76 Computer software 3 QE Geology 3 QP Physiology 3 TC Hydraulic engineering. Ocean engineering 3