1982/83 End office connection study: Analog voice and voiceband data transmission performance characterization of the public switched network. - Michele B. Carey; Han-Tee Chen; Alfred Descloux; James F. Ingle; Kun Il Park (AT&T Bell Lab. Tech. J., 1984)

1983 Exchange Access Study: Analog Voice-Frequency Transmission Performance Characterization of the Exchange Access Plant. - James F. Ingle; Kun Park; Thomas C. Redman (IEEE Trans. Commun., 1987)