Doug Schaffer Zhengping Zuo Saul Greenberg Lyn Bartram John Dill Shelli Dubs Mark Roseman Navigating Hierarchically Clustered Networks Through Fisheye and Full-Zoom Methods. 162-188 1996 3 ACM Trans. Comput.-Hum. Interact. 2 db/journals/tochi/tochi3.html#SchafferZGBDDR96 http://doi.acm.org/10.1145/230562.230577