Axel Simon Andy King Convex hull of planar h-polyhedra. 259-271 2004 81 Int. J. Comput. Math. 3 http://taylorandfrancis.metapress.com/openurl.asp?genre=article&issn=0020-7160&volume=81&issue=3&spage=259 db/journals/ijcm/ijcm81.html#SimonK04