US Army, Technical Manual, TM 5-6675-296-14, THEODOLITE, DIRECTIONAL: 0.002 MIL GRADU 5.9 INCH LG TELESCOPE, DETACHABLE TRIBRACH W/ACCESSORIES AND TR, ... T2-67MIL AND T2-68MIL), (6675-00-98
US Army, Technical Manual, TM 5-6675-200-14, THEODOLITE: DIRECTIONAL; 5.9 INCH LONG TELESCOPE; DETACHABLE TRIBRACH W/ACCESSORIES AND TRIPOD, (WILD HEERBRUGG