John Blatz, Erin Fitzgerald, George Foster, Simona Gandrabur, Cyril Goutte, Alex Kulesza, Alberto Sanchis, Nicola Ueffing,
Confidence estimation for machine translation Proceedings of the 20th international conference on Computational Linguistics - COLING '04. pp. 315- 321 ,(2004) ,
10.3115/1220355.1220401