Debashis Bera Madhumangal Pal Tapan Kumar Pal An Efficient Algorithm for Finding All Hinge Vertices on Trapezoid Graphs. 17-27 2003 36 Theory Comput. Syst. 1 http://dx.doi.org/10.1007/s00224-002-1004-3 db/journals/mst/mst36.html#BeraPP03