Sifting through hierarchical information. - Doug Schaffer; Saul Greenberg (INTERCHI Adjunct Proceedings, 1993)

Navigating Hierarchically Clustered Networks Through Fisheye and Full-Zoom Methods. - Doug Schaffer; Zhengping Zuo; Saul Greenberg; Lyn Bartram; John Dill; Shelli Dubs; Mark Roseman (ACM Trans. Comput. Hum. Interact., 1996)