@inproceedings{STOC-1988-PapadimitriouY88a,
	author        = "Christos H. Papadimitriou and Mihalis Yannakakis",
	booktitle     = "{Proceedings of the 20th Annual ACM Symposium on Theory of Computing}",
	doi           = "10.1145/62212.62233",
	isbn          = "0-89791-264-0",
	pages         = "229--234",
	publisher     = "{ACM}",
	title         = "{Optimization, Approximation, and Complexity Classes}",
	year          = 1988,
}