Unobtrusive Multimodal Biometrics for Ensuring Privacy and Information Security with Personal Devices. - Elena Vildjiounaite; Satu-Marja Mäkelä; Mikko Lindholm; Reima Riihimäki; Vesa Kyllönen; Jani Mäntyjärvi; Heikki Ailisto (Pervasive, 2006)