Morteza Zahedi Philippe Dreuw David Rybach Thomas Deselaers Hermann Ney Geometric Features for Improving Continuous Appearance-based Sign Language Recognition. 1019-1028 2006 BMVC https://doi.org/10.5244/C.20.104 conf/bmvc/2006 db/conf/bmvc/bmvc2006.html#ZahediDRDN06