1. 3D Knowledge. http://3dk.asu.edu.
2. Milos Sramek's volume visualization page. http://www.viskom.oeaw.ac.at/milos/.
3. National design repository. http://edge.mcs.drexel.edu/repository/frameset.html.
4. 3D Shape Retrieval at the University of Bonn; 2003. http://www.cg.cs.uni-bonn.de/project-pages/3dsearch/.
5. Princeton Shape Benchmark; 2003. http://shape.cs.princeton.edu/benchmark/index.cgi.