TA Engineering (General). Civil engineering (General) 23 TJ Mechanical engineering and machinery 19 TK Electrical engineering. Electronics Nuclear engineering 13 QA75 Electronic computers. Computer science 7 TP Chemical technology 7 QA Mathematics 5 NA Architecture 4 T Technology (General) 4 TH Building construction 4 G70.212-70.215 Geographic information system 3 Q Science (General) 3 HE Transportation and Communications 2 LB Theory and practice of education 2 QC Physics 2 QH Natural history 2 TC Hydraulic engineering. Ocean engineering 2 Unspecified 2 G Geography (General) 1 GA Mathematical geography. Cartography 1 QD Chemistry 1 QE Geology 1 QH301 Biology 1 RK Dentistry 1 T58.5-58.64 Information technology 1 TG Bridge engineering 1 TH434-437 Quantity surveying 1 TL Motor vehicles. Aeronautics. Astronautics 1 TT Handicrafts Arts and crafts 1