external controls external cooling external cooperation external corrosion external cost external costs external costs of transport external covering external credit external current external customer external customers external cylindrical external damage external data external data protection external data sources external database external databases external debt external debt burden external debt crisis external debt sustainability external defibrillators external deficits external demand external dependencies external design external development external developments external device external devices external diameter external digital external dimension external dimensions external directors external disk external display external distractions external disturbances external documents external donor external donors external door external doors external drive external drives external ear external ear canal external ears external economic external economic relations external editor external effect external effects external electric external electrical external electrodes external electron external electronic external element external elements external emergency external end external enemies external enemy external energy external energy policy external entities external entity external envelope external environment external environmental external environments external equipment external evaluation external evaluations external evaluator external evaluators external event external events external evidence external examination external examinations external examiner external expert external expertise external experts external exposure external face external faces external facilities external factor external factors external factors affecting external factors influencing external features external field