The Bell System Technical Journal, volume 50 no. 8, October 1971.
AT&T, October 1971, pp 2495 - 2856 inclusive, references, diagrams.
AT&T, October 1971, pp 2495 - 2856 inclusive, references, diagrams.
American Telephone and Telegraph Co., NY 1963, pp 2501-2974 inclusive, diagrams, some photos, references.
American Telephone and Telegraph Co., NY 1965, pp 547-729 inclusive, diagrams, some photos, references.
AT&T, March 1965, pp 373-pp 546 inclusive, references, diagrams.
AT&T 1965, pp 207-372 inclusive, diagrams and photographs, references.
Bell Tel. Labs, NY 1947, 1956, 1963, 43 pages, diagrams, tables, references.
Bell System, November 1970, pp 1995-2415 inclusive, diagrams, references, some photographs.
AES, Audio Engineering Society, NY 1968; pp 258-384 inclusive, double-column text, photographs, diagrams, references, advertisements, etc.
Bell Telephone Laboratories, November 1926, Reprint B-212, reprint of a paper presented at annual meeting of telegraph and telephone section of the Ameircan Railway Association September1926; and published in their Proceedings; 16 pages, some illustr.
AT&T, issued October 1953, orig. published in The Bell System Technical Journal, vol 32, March 1953; 24 pages plus rear foldout chart.