1. Capabilities of the Telephone Network for Data Transmission;Alexander;Bell System Technical Journal,1960
2. Bell System Technical Journals on Conditioned Lines American Telephone and Telegraph Company Bedminster, NJ 1969-1971
3. Theoretical Fundamentals of Pulse Transmission-I;Sunde;Bell System Technical Journal,1954
4. Bandpass Filtering with Lowpass Filters;Urkowitz;Journal of the Franklin Institute,1963