Nir Andelman Yishay Mansour Auctions with Budget Constraints. 26-38 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3111&spage=26 2004 conf/swat/2004 SWAT db/conf/swat/swat2004.html#AndelmanM04