Siu-Wing Cheng Hyeon-Suk Na Antoine Vigneron Yajun Wang Approximate Shortest Paths in Anisotropic Regions. 802-824 2008 38 SIAM J. Comput. 3 http://dx.doi.org/10.1137/06067777X db/journals/siamcomp/siamcomp38.html#ChengNVW08