Amit Chakrabarti Chandra Chekuri Anupam Gupta Amit Kumar Approximation Algorithms for the Unsplittable Flow Problem. 51-66 2002 conf/approx/2002 APPROX http://link.springer.de/link/service/series/0558/bibs/2462/24620051.htm db/conf/approx/approx2002.html#ChakrabartiCGK02