電話按鍵 Bell System Technical Journal 61(5) 821–839 (May–June 1982) B.L. Hanson, A Brief History of Applied Behavioral Science at Bell Laboratories, Bell System
喬治·H·米利 George H., A method for synthesizing sequential circuits, Bell System Technical Journal, 1955, 34 (5): 1045–1079, MR 0073450, doi:10.1002/j.1538-7305
摆钟Marrison, Warren. The Evolution of the Quartz Crystal Clock. Bell System Technical Journal. 1948, 27: 510–588. doi:10.1002/j.1538-7305.1948.tb01343.x.