1. Turtle Geometry: The Computer as a Medium for Exploring Mathematics;Abelson,1982
2. Steps into a Geometer's Workbench;Akman,1987
3. Unobstructed Shortest Paths in Polyhedral Environments;Akman,1987
4. Excursions to a topological picturebook;Akman,1991
5. Implementing a topological picturebook;Akman,1991