Sukumar Mondal Madhumangal Pal Tapan Kumar Pal Optimal Sequential and Parallel Algorithms to Compute a Steiner Tree on Permutation Graphs. 937-943 2003 80 Int. J. Comput. Math. 8 http://taylorandfrancis.metapress.com/openurl.asp?genre=article&issn=0020-7160&volume=80&issue=8&spage=937 db/journals/ijcm/ijcm80.html#MondalPP03