Towards Ubiquitous Learning 6th European Conference of Technology Enhanced Learning, EC-TEL 2011, Palermo, Italy, September 20-23, 2011. Proceedings - Kloos, Carlos Delgado; Gillet, Denis; Crespo García, Raquel M.; Wild, Fridolin; Wolpers, Martin (Springer Berlin Heidelberg : Imprint: Springer, 2011)