Ilya D. Rosenberg Alexander Grau Charles Hendee Nadim Awad Ken Perlin IMPAD: an inexpensive multi-touchpressure acquisition device. 3217-3222 2009 CHI Extended Abstracts http://doi.acm.org/10.1145/1520340.1520460 conf/chi/2009a db/conf/chi/chi2009a.html#RosenbergGHAP09