MIL-P-10088, MILITARY SPECIFICATION: PERISCOPE, M13B1 (12-JAN-1950) [NO S/S DOCUMENT]

MIL-P-10088, MILITARY SPECIFICATION: PERISCOPE, M13B1 (12-JAN-1950) [NO S/S DOCUMENT]., This specification covers one type of periscope known as Periscope M13B1