t1-995 technology
ta1-2040 engineering/civil engineering
tc1-978 hydraulic engineering
tc1501-1800 ocean engineering
td1-1066 environmental technology
te1-450 highway engineering
tf1-1620 railroad engineering
tg1-470 bridge engineering
th1-9745 building construction
tj1-1570 mechanical engineering
tk1-9971 electrical engineering
tl1-4050 motor vehicles. aeronautics. astronautics
tp1-1185 chemical technology
ts1-2301 manufactures