TP Chemical technology 407 TJ Mechanical engineering and machinery 171 TA Engineering (General). Civil engineering (General) 116 QD Chemistry 113 TK Electrical engineering. Electronics Nuclear engineering 107 QC Physics 85 Q Science (General) 48 QA Mathematics 38 T Technology (General) 25 TS Manufactures 19 TD Environmental technology. Sanitary engineering 18 Unspecified 13 TH Building construction 12 QH Natural history 9 R Medicine (General) 9 G70.39-70.6 Remote sensing 8 QA75 Electronic computers. Computer science 8 QP Physiology 8 NA Architecture 6 TE Highway engineering. Roads and pavements 6 QR Microbiology 5 TC Hydraulic engineering. Ocean engineering 5 G70.212-70.215 Geographic information system 4 GE Environmental Sciences 4 HD1394-1394.5 Real estate management 3 QH301 Biology 3 T58.5-58.64 Information technology 3 HD28 Management. Industrial Management 2 HE Transportation and Communications 2 HT101-395 Sociology, Urban 2