TJ Mechanical engineering and machinery 216 TK Electrical engineering. Electronics Nuclear engineering 143 TA Engineering (General). Civil engineering (General) 111 TP Chemical technology 106 L Education (General) 32 QD Chemistry 29 T Technology (General) 29 QA75 Electronic computers. Computer science 24 LB Theory and practice of education 19 Q Science (General) 14 Machine design and drawing 12 QA Mathematics 12 QC Physics 11 TS Manufactures 10 Unspecified 9 TH Building construction 6 Mechanics applied to machinery. Dynamics 5 QH Natural history 5 Design 4 Experimental 4 Marketing 4 Performance 4 Temperature 4 Textiles 4 Concrete 3 Electromyography 3 Experimental design 3 H Social Sciences (General) 3 HD28 Management. Industrial Management 3 Heuristics 3