Beth Ann Hockey Oliver Lemon Ellen Campana Laura M. Hiatt Gregory Aist James Hieronymus John Dowding Alexander Gruenstein Targeted Help for Spoken Dialogue Systems. 147-154 2003 EACL http://acl.ldc.upenn.edu/E/E03/E03-1075.pdf db/conf/eacl/eacl2003.html#HockeyLCHAHDG03