@inproceedings{CSCW-2000-Sun,
	author        = "Chengzheng Sun",
	booktitle     = "{Proceedings of the Eighth ACM Conference on Computer Supported Cooperative Work}",
	doi           = "10.1145/358916.358990",
	isbn          = "1-58113-222-0",
	pages         = "191--200",
	publisher     = "{ACM}",
	title         = "{Undo any operation at any time in group editors}",
	year          = 2000,
}