TK Electrical engineering. Electronics Nuclear engineering 132 TP Chemical technology 109 TJ Mechanical engineering and machinery 73 TA Engineering (General). Civil engineering (General) 38 QA75 Electronic computers. Computer science 28 QA Mathematics 15 QD Chemistry 12 T Technology (General) 12 Q Science (General) 10 TS Manufactures 8 Unspecified 6 HD28 Management. Industrial Management 5 TH Building construction 5 NA Architecture 4 QC Physics 4 QH Natural history 4 QA76 Computer software 3 TE Highway engineering. Roads and pavements 3 TK7885-7895 Computer engineer. Computer hardware 3 G70.212-70.215 Geographic information system 2 HD Industries. Land use. Labor 2 L Education (General) 2 R Medicine (General) 2 T58.5-58.64 Information technology 2 BP Islam. Bahaism. Theosophy, etc 1 GV Recreation Leisure 1 LB Theory and practice of education 1 QH301 Biology 1 QH426 Genetics 1 QK Botany 1