TP Chemical technology 119 TK Electrical engineering. Electronics Nuclear engineering 73 TA Engineering (General). Civil engineering (General) 68 QA Mathematics 59 QA75 Electronic computers. Computer science 50 TJ Mechanical engineering and machinery 45 T Technology (General) 27 QD Chemistry 26 QC Physics 18 L Education (General) 14 Q Science (General) 14 HD28 Management. Industrial Management 11 QA76 Computer software 10 HD Industries. Land use. Labor 9 H Social Sciences (General) 8 GE Environmental Sciences 7 HD1394-1394.5 Real estate management 7 LB Theory and practice of education 7 NA Architecture 6 TH Building construction 6 G Geography (General) 5 G70.212-70.215 Geographic information system 5 QH Natural history 5 Q Science 4 TD Environmental technology. Sanitary engineering 4 TH434-437 Quantity surveying 4 Unspecified 4 G70.39-70.6 Remote sensing 3 HF Commerce 3 QE Geology 2