@inproceedings{STOC-2003-Plaxton,
	author        = "C. Greg Plaxton",
	booktitle     = "{Proceedings of the 35th Annual ACM Symposium on Theory of Computing}",
	doi           = "10.1145/780542.780549",
	isbn          = "1-58113-674-9",
	pages         = "40--49",
	publisher     = "{ACM}",
	title         = "{Approximation algorithms for hierarchical location problems}",
	year          = 2003,
}