Bruno Dumas Denis Lalanne Sharon L. Oviatt Multimodal Interfaces: A Survey of Principles, Models and Frameworks. 3-26 2009 Human Machine Interaction http://dx.doi.org/10.1007/978-3-642-00437-7_1 series/lncs/5440 db/series/lncs/lncs5440.html#DumasLO09