Patrick Briest Parinya Chalermsook Sanjeev Khanna Bundit Laekhanukit Danupon Nanongkai Improved Hardness of Approximation for Stackelberg Shortest-Path Pricing. 444-454 2010 WINE http://dx.doi.org/10.1007/978-3-642-17572-5_37 conf/wine/2010 db/conf/wine/wine2010.html#BriestCKLN10