Rachel Matichin David Peleg Approximation Algorithm for Hotlink Assignments in Web Directories. 271-280 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2748&spage=271 2003 conf/wads/2003 WADS db/conf/wads/wads2003.html#MatichinP03