Switchboards BD-71, BD-72, BD-72-A and BD-72-B - USA Voorschrift, Technical Manual, 11-330 Switchboard BD-96 : repair instructions operational requirements - USA Voorschrift, Technical Manual, 11-4314 Signal Training. Pamphlet no. 8. Signal Office Organization and Procedure. Part II. Procedure for Telephone Switchboard Operating. 1945 - Engeland Voorschrift Working Instructions. Switchboard F and F, MK I, MK I* and MK II. WO 1016 - Engeland Voorschrift
