@inproceedings{STOC-1991-AgrawalKR,
	author        = "Ajit Agrawal and Philip N. Klein and R. Ravi",
	booktitle     = "{Proceedings of the 23rd Annual ACM Symposium on Theory of Computing}",
	doi           = "10.1145/103418.103437",
	isbn          = "0-89791-397-3",
	pages         = "134--144",
	publisher     = "{ACM}",
	title         = "{When Trees Collide: An Approximation Algorithm for the Generalized Steiner Problem on Networks}",
	year          = 1991,
}