Enhanced Good-Turing and Cat-Cal: Two New Methods for Estimating Probabilities of English Bigrams (abbreviated version) Kenneth W Church author William A Gale author 1989 text Speech and Natural Language: Proceedings of a Workshop Held at Cape Cod, Massachusetts, October 15-18, 1989 conference publication church-gale-1989-enhanced https://aclanthology.org/H89-2013/ 1989