TK Electrical engineering. Electronics Nuclear engineering 33 TJ Mechanical engineering and machinery 20 QC Physics 12 TA Engineering (General). Civil engineering (General) 12 T Technology (General) 8 QA75 Electronic computers. Computer science 7 QA Mathematics 4 QH301 Biology 4 TP Chemical technology 4 HD1394-1394.5 Real estate management 3 QA76 Computer software 3 Q Science (General) 2 QH Natural history 2 TD Environmental technology. Sanitary engineering 2 TH Building construction 2 G Geography (General) 1 G70.212-70.215 Geographic information system 1 HN Social history and conditions. Social problems. Social reform 1 HX Socialism. Communism. Anarchism 1 LB2300 Higher Education 1 Q Science 1 QD Chemistry 1 TC Hydraulic engineering. Ocean engineering 1 Unspecified 1