external technical external telephone external temperature external temperature sensor external temperatures external terminal external territories external thermal external things external third external thread external threads external threat external threats external time external timer external tool external tools external trade external trade policy external trade statistics external training external transactions external translation external transport external trauma external treatment external trigger external tube external unit external units external use external user external users external vacuum external validation external validity external value external variables external verification external video external view external views external voltage external wall external walls external water external web external website external websites external work external world external wounds externalised externalities externality externalize externalized externalizing externally externally accessible externally and internally externally applied externally funded externally imposed externally mounted externally provided externally threaded externally visible extinct extinct animal extinct animals extinct birds extinct due extinct family extinct genus extinct group extinct in the wild extinct language extinct languages extinct now extinct order extinct species extinct volcano extinct volcanoes extinct when extinction extinction coefficient extinction coefficients extinction crisis extinction due extinction event extinction events extinction level extinction of species extinction of the dinosaurs extinction of the human extinction rate extinction rates