@inbook {gohnert_flexible_2009,
	title = {A flexible multi-mode undo mechanism for a collaborative modeling environment},
	booktitle = {Groupware: Design, Implementation, and Use},
	year = {2009},
	note = {00002},
	publisher = {Springer},
	organization = {Springer},
	author = {G{\"o}hnert, Tilman and Nils Malzahn and H. Ulrich Hoppe}
}
