Abul Kashem M. Ziaur Rahman An Optimal Parallel Algorithm for c-Vertex-Ranking of Trees. 464-473 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2906&spage=464 2003 conf/isaac/2003 ISAAC db/conf/isaac/isaac2003.html#KashemR03