Rohit Khandekar Tracy Kimbrel Konstantin Makarychev Maxim Sviridenko On Hardness of Pricing Items for Single-Minded Bidders. 202-216 2009 APPROX-RANDOM http://dx.doi.org/10.1007/978-3-642-03685-9_16 conf/approx/2009 db/conf/approx/approx2009.html#KhandekarKMS09