Piyanuch Silapachote Allen R. Hanson Richard S. Weiss A Hierarchical Approach to Sign Recognition. 22-28 2005 conf/wacv/2005 WACV/MOTION http://doi.ieeecomputersociety.org/10.1109/ACVMOT.2005.6 db/conf/wacv/wacv2005.html#SilapachoteHW05