David Wible Chin-Hwa Kuo Meng Chang Chen Nai-Lung Tsao Chong-Fu Hong A Ubiquitous Agent for Unrestricted Vocabulary Learning in Noisy Digital Environments. 503-512 2006 conf/its/2006 Intelligent Tutoring Systems http://dx.doi.org/10.1007/11774303_50 db/conf/its/its2006.html#WibleKCTH06