Hendrik Witt Tom Nicolai Holger Kenn Designing a Wearable User Interface for Hands-free Interaction in Maintenance Applications. 652-655 2006 conf/percom/2006w PerCom Workshops http://doi.ieeecomputersociety.org/10.1109/PERCOMW.2006.39 db/conf/percom/percomw2006.html#WittNK06