Using cluster analysis to guide interface design for audiotext services. - Eileen C. Schwab; Amy L. Schwartz (INTERCHI Adjunct Proceedings, 1993)

Increasing the Usability of Interactive Voice Response Systems: Research and Guidelines for Phone-Based Interfaces. - Robert M. Schumacher Jr.; Mary L. Hardzinski; Amy L. Schwartz (Hum. Factors, 1995)