Line units BE-77, BE-77-A and BE-77-B - USA Voorschrift, Technical Manual, 11-359 Complete 100-mile spiral-four carrier system - USA Voorschrift, Technical Manual, 11-2001 Storage batteries for signal communication except those pertaining to aircraft - USA Voorschrift, Technical Manual, 11-430 Electrical communication systems equipment - USA Voorschrift, Technical Manual, 11-487 Handbook no. 2c(2). Communications for Beach and Build-Up Oraganisation. WO 8620 - Engeland Voorschrift
