Vijay Chandru Ramesh Hariharan Narasimha M. Krishnakumar Short-Cuts on Star, Source and Planar Unfoldings. 174-185 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3328&spage=174 2004 conf/fsttcs/2004 FSTTCS db/conf/fsttcs/fsttcs2004.html#ChandruHK04