@inproceedings{STOC-1985-VardiS,
	author        = "Moshe Y. Vardi and Larry J. Stockmeyer",
	booktitle     = "{Proceedings of the 17th Annual ACM Symposium on Theory of Computing}",
	doi           = "10.1145/22145.22173",
	pages         = "240--251",
	publisher     = "{ACM}",
	title         = "{Improved Upper and Lower Bounds for Modal Logics of Programs: Preliminary Report}",
	year          = 1985,
}