EN 50008 : low voltage switchgear and controlgear for industrial use. Inductive proximity switches. Form A, for direct current, 3 or 4 terminals / European Commitee for electrothecnical Standardization
EN 50010 : low voltage switchgear and controlgear for industrial use. Inductive proximity switches. Methods for measuring the operating distance and operating frequency / European Commitee for electrothecnical Standardization
Relatório [texto policopiado] / CEDITC - Comissão para o Estudo do Desenvolvimento Institucional e Tecnológico das Comunicações