TP Chemical technology 68 TK Electrical engineering. Electronics Nuclear engineering 59 QA75 Electronic computers. Computer science 56 TA Engineering (General). Civil engineering (General) 45 L Education (General) 38 Q Science (General) 24 QD Chemistry 23 LB Theory and practice of education 18 HD28 Management. Industrial Management 17 TJ Mechanical engineering and machinery 15 QA Mathematics 12 T Technology (General) 12 QC Physics 8 QH Natural history 8 H Social Sciences (General) 7 HD Industries. Land use. Labor 7 NA Architecture 6 QA76 Computer software 6 LB1603 Secondary Education. High schools 5 QH301 Biology 5 TH434-437 Quantity surveying 4 HE Transportation and Communications 3 QE Geology 3 TH Building construction 3 BP Islam. Bahaism. Theosophy, etc 2 G70.212-70.215 Geographic information system 2 HB Economic Theory 2 HG Finance 2 NA9000-9284 City planning 2 QP Physiology 2