QA75 Electronic computers. Computer science 47 TK Electrical engineering. Electronics Nuclear engineering 39 TA Engineering (General). Civil engineering (General) 13 NA Architecture 11 T Technology (General) 8 TP Chemical technology 8 L Education (General) 6 Q Science (General) 5 QA76 Computer software 5 TJ Mechanical engineering and machinery 5 TT Handicrafts Arts and crafts 5 HD Industries. Land use. Labor 4 TH Building construction 4 BP Islam. Bahaism. Theosophy, etc 3 NX Arts in general 3 TS Manufactures 3 G154.9-155.8 Travel and state. Tourism 2 G70.212-70.215 Geographic information system 2 GV Recreation Leisure 2 HD28 Management. Industrial Management 2 HE Transportation and Communications 2 HT101-395 Sociology, Urban 2 NK Decorative arts Applied arts Decoration and ornament 2 PE English 2 QA Mathematics 2 QC Physics 2 QM Human anatomy 2 T58.5-58.64 Information technology 2 TD Environmental technology. Sanitary engineering 2 TH434-437 Quantity surveying 2