1. Members of the Technical Staff, Bell Telephone Laboratories, Transmission Systems for Communications (Winston-Salem: Western Electric Company, 1971).
2. CCITT Blue Book, vol. III.2, International Analogue Carrier Systems (Geneva: ITU, 1989).
3. Data Communications Using Voiceband Private Line Channels, Bell System Tech. Ref. Pub. 41004 (New York: AT&T, 1973).
4. Transmission Parameters Affecting Voiceband Data Transmission-Description of Parameters, Bell System Tech. Ref. Pub. 41008 (New York: AT&T, 1974).
5. ITU-T Rec. M.1020, Characteristics of Special Quality International Leased Circuits with Special Bandwidth Conditioning, 1993.