TK Electrical engineering. Electronics Nuclear engineering 1,132 TJ Mechanical engineering and machinery 562 TA Engineering (General). Civil engineering (General) 280 TP Chemical technology 190 QA75 Electronic computers. Computer science 172 T Technology (General) 155 QA Mathematics 148 Q Science (General) 85 QC Physics 76 QD Chemistry 34 TH Building construction 31 QA76 Computer software 30 HE Transportation and Communications 28 Unspecified 25 TC Hydraulic engineering. Ocean engineering 24 TK5101-6720 Telecommunication 23 NA Architecture 20 Simulation 18 TL Motor vehicles. Aeronautics. Astronautics 16 TK7885-7895 Computer engineer. Computer hardware 14 R Medicine (General) 13 Machine design and drawing 12 Mechanics applied to machinery. Dynamics 12 QH Natural history 12 Antennas 11 QH301 Biology 11 TD Environmental technology. Sanitary engineering 11 HD Industries. Land use. Labor 10 L Education (General) 10 TE Highway engineering. Roads and pavements 10