Bell System Technical Journal volume XXXV, number 1, January 1956; volume 30 no. 1.
AT&T 1956; pp 1 - 245 inclusive; photographs, diagrams; references.
AT&T 1956; pp 1 - 245 inclusive; photographs, diagrams; references.
American Telephone & Telegraph, NY 1932; complete separate January issue; 196 pages.