The Bell System History book that Lisa referred to is: A History of Science & Engineering in the Bell System: Communications Sciences,
1925-1980. The ISBN is 0-932764-06-1. It is available from
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(and numerous others) starting at $32.28. I have a copy. Google the ISBN for other sources.
Regards,
Charles G. Gray Senior Lecturer, Telecommunications Oklahoma State University - Tulsa (918) 594-8433