Bell System Technical Journal, Tables of Contents and Cumulative Index, volumes XXI XXX, 1942 - 1951.
American Telephone & Telegraph Co, NY, n.d., ca. 1952; 32 pages.
American Telephone & Telegraph Co, NY, n.d., ca. 1952; 32 pages.
AT&T 1965, pp 207-372 inclusive, diagrams and photographs, references.