208 BELL SYSTEM TECHNICAL JOURNAL 



12. Clark, A. B., "Telephone Transmission over Long Cable Circuits," A. I. E. E., 



Trans., Vol. 42, pp. 86-96, 1923. 



13. Green, E. I., "Transmission Characteristics of Open-Wire Telephone Lines," 



A. I. E. E., Trans., Vol. 49, pp. 1524-1535, 1930. 



14. Affel, H. A., Demarest, C. S., and Green, C. W., "Carrier Systems on Long 



Distance Telephone Lines," Bell Sys. Tech. Jour., Vol. 7, pp. 564-629, 1928; 

 A. I. E. E., Trans., Vol. 47, pp. 1360-1387, 1928. 



15. O'Leary, J. T., Blessing, E. C., and Beyer, J. W., "Improved Three-Channel 



Carrier Telephone System," Bell Sys. Tech. Jour., Vol. 18, pp. 49-75, 1939. 



16. Cowley, G. W., "Volume Limiter Circuits," Bell Labs. Record, Vol. 15, pp. 



311-315, June, 1937. 



17. Peterson, Eugene and Keith, C. R., "Grid Current Modulation," Bell Sys. Tech. 



Jour., Vol. 7, pp. 106-139, 1928. 



18. Nyquist, H., Shanck, R. B., and Cory, S. L, "Measurement of Telegraph Trans- 



mission," A. I. E. E., Trans., Vol. 46, pp. 367-376, 1927. 



19. Shanck, R. B., Cowan, F. A., and Cory, S. L, "Recent Developments in the 



Measurement of Telegraph Transmission," Bell Sys. Tech. Jour., Vol. 18, 

 pp. 143-189, 1939. 



20. Kupfmuller, K., " Uber Einschwingvorgange in Wellenfiltern," E. N. T., Vol. 1, 



pp. 141-152, 1924. 



21. Nyquist, H., "Certain Topics in Telegraph Transmission Theory," A. L E. E., 



rmM5., Vol. 47, pp. 617-644, 1928. 



22. Stahl, H., "Versuche iiber eine gunstige Verteilung der Tragerwellen in der 



Wechselstromtelegraphie," T. F. T., Vol. 19, pp. 340-347, 1930. 



23. Herman, J., " Bias Control in Telegraph Communication," U. S. Patent 1,886,808, 



Nov. 8, 1932; "Transmission Level Control in Telegraph Signaling Systems," 

 U. S. Patent 1,943,478, Jan. 16, 1934. 



24. Cash, C. C, "Protection against Lightning Interference," Bell Labs. Record, 



Vol. 15, pp. 125-128, Dec, 1936. 



25. Trucksess, D. E., "High Precision Speed Regulator," Bell Labs. Record, Vol. 13, 



pp. 187-190, Feb., 1935. 



26. Fry, J. R. and Gardner, L. A., "Polarized Telegraph Relays," A. I. E. E., Trans., 



Vol. 44, pp. 333-338, 1925. 



