QA75 Electronic computers. Computer science 46 TK Electrical engineering. Electronics Nuclear engineering 30 TA Engineering (General). Civil engineering (General) 27 QA Mathematics 21 NA Architecture 17 L Education (General) 14 TJ Mechanical engineering and machinery 13 QA76 Computer software 11 T Technology (General) 9 TH Building construction 9 TP Chemical technology 8 H Social Sciences (General) 7 G Geography (General) 6 HD Industries. Land use. Labor 6 LB Theory and practice of education 6 G70.212-70.215 Geographic information system 5 Q Science (General) 5 QC Physics 5 HD1394-1394.5 Real estate management 4 HT101-395 Sociology, Urban 4 LB2300 Higher Education 4 QE Geology 3 QH301 Biology 3 G154.9-155.8 Travel and state. Tourism 2 LB1603 Secondary Education. High schools 2 T Technology 2 A General Works 1 BP Islam. Bahaism. Theosophy, etc 1 BV1460 Religious Education 1 GE Environmental Sciences 1