Christian Wallraven Veronica Sundstedt Proceedings of the 4th Symposium on Applied Perception in Graphics and Visualization, APGV 2007, Tübingen, Germany, July 25-27, 2007 253 2007 978-1-59593-670-7 APGV ACM International Conference Proceeding Series ACM db/conf/apgv/apgv2007.html