1. 3) Ó'Dúnlaing, C., Yap, K. : A “Retraction” Method for Planning the Motion of a Disc, Journal of Algorithms, Vol. 6, Issue 1, pp. 104-111, 1985.
2. 4) Chithambaram, R., Beard, K., and Barrera, R. : Skeletonizing polygons for map generalization, Technical Papers, ACSM-ASPRS Convention, Cartography and GIS/LIS, Vol. 2, pp. 44-55, 1991.
3. 5) Aichholzer, O., Alberts, D., Aurenhammer, F., Gärtner, B. : A Novel Type of Skeleton for Polygons, Journal of Universal Computer Science, Vol. 1, No. 12, pp. 752-761, 1995.
4. 6) Walter, V., Kada, M. and Chen, H. : Shortest path analyses in raster maps for pedestrian navigation in location based systems, International Symposium on “Geospatial Databases for Sustainable Development”, ISPRS Technical Commission IV, CD-ROM, 2006.
5. 7) Nilsson, N. J. : A Mobile Automaton: An Application of Artificial Intelligence Techniques, Proc. IJCAI, pp. 509-520, 1969.