TP Chemical technology 102 TA Engineering (General). Civil engineering (General) 70 TD Environmental technology. Sanitary engineering 25 TK Electrical engineering. Electronics Nuclear engineering 24 QD Chemistry 14 Q Science (General) 12 T Technology (General) 12 TJ Mechanical engineering and machinery 11 QA Mathematics 4 GE Environmental Sciences 3 QH Natural history 3 TC Hydraulic engineering. Ocean engineering 3 TN Mining engineering. Metallurgy 3 QH301 Biology 2 Unspecified 2 G70.39-70.6 Remote sensing 1 HD1394-1394.5 Real estate management 1 HD28 Management. Industrial Management 1 HJ Public Finance 1 QE Geology 1