Development of a Usable Graphical User Interface Design Guide. - Robert M. Schumacher Jr.; Arnold M. Lund (HCI (2), 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)