Instructions for adjusting, operating and managing / Western Electric Company
Constitución de las instalaciones telefónicas automáticas : tomo I: Equipos y funcionamiento / Kurt Trautmann; Siemens
Single-sided rack equipment : Strowger automatic telephones / Automatic Telephone Manufacturing Company Ltd.
The layout of "Strowger" automatic exchanges : Strowger automatic telephones / Automatic Telephone Manufacturing Company Ltd.