@inproceedings{lehmann2012,
	Author = {Lehmann, Janette and Lalmas, Mounia and Yom-Tov, Elad and Dupret, Georges},
	Booktitle = {Proceedings of the Conference on User Modeling, Adaptation, and Personalization},
	Pages = {164--175},
	Publisher = {Springer},
	Series = {UMAP},
	Title = {Models of user engagement},
	Year = {2012},
}