Gregor Broll Susanne Keck Paul Holleis Andreas Butz Improving the accessibility of NFC/RFID-based mobile interaction through learnability and guidance. 2009 Mobile HCI http://doi.acm.org/10.1145/1613858.1613906 conf/mhci/2009 db/conf/mhci/mhci2009.html#BrollKHB09