Rajiv Gandhi Samir Khuller Aravind Srinivasan Nan Wang Approximation Algorithms for Channel Allocation Problems in Broadcast Networks. 47-58 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2764&spage=47 2003 conf/random/2003 RANDOM-APPROX db/conf/random/random2003.html#GandhiKSW03