Avrim Blum Shuchi Chawla David R. Karger Terran Lane Adam Meyerson Maria Minkoff Approximation Algorithms for Orienteering and Discounted-Reward TSP. 46-55 2003 conf/focs/2003 FOCS http://csdl.computer.org/comp/proceedings/focs/2003/2040/00/20400046abs.htm db/conf/focs/focs2003.html#BlumCKLMM03