Simon Holland David R. Morse Henrik Gedenryd Direct Combination: A New User Interaction. 108-122 2002 conf/mhci/2002 Mobile HCI http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2411&spage=0108 db/conf/mhci/mhci2002.html#HollandMG02