Air corps : Flying; general - USA Voorschrift, Army Regulations, No. 95-15 Air corps : Army railways communications system - USA Voorschrift, Army Regulations, No. 95-200 Air corps : Airdromes - USA Voorschrift, Army Regulations, 95-35 Telephone Terminal Set TC-21 (N) (Carrier) - USA Voorschrift, Technical Manual, 11-341