TK Electrical engineering. Electronics Nuclear engineering 408 TA Engineering (General). Civil engineering (General) 390 TP Chemical technology 385 TJ Mechanical engineering and machinery 293 QA75 Electronic computers. Computer science 255 T Technology (General) 197 QA Mathematics 160 Q Science (General) 145 QD Chemistry 94 L Education (General) 92 QC Physics 92 HD28 Management. Industrial Management 66 QA76 Computer software 53 BP Islam. Bahaism. Theosophy, etc 50 TH Building construction 41 H Social Sciences (General) 39 HD1394-1394.5 Real estate management 37 HD Industries. Land use. Labor 34 NA Architecture 33 LB2300 Higher Education 32 Q Science 32 TD Environmental technology. Sanitary engineering 30 TN Mining engineering. Metallurgy 22 R Medicine (General) 19 LB Theory and practice of education 18 LC Special aspects of education 18 T Technology 17 TH434-437 Quantity surveying 16 G Geography (General) 15 LB1603 Secondary Education. High schools 15