M. Banko, M. Cafarella, S. Soderland, M. Broadhead, and O. Etzioni. Proceedings of the 20th International Joint Conference on Artifical Intelligence, page 2670--2676. San Francisco, CA, USA, Morgan Kaufmann Publishers Inc., (2007)
J. Puzicha, T. Hofmann, and J. Buhmann. Computer Vision and Pattern Recognition, 1997. Proceedings., 1997
IEEE Computer Society Conf. on, page 267--272. (1997)