P. Terenziani, C. Carlini, und S. Montani. Temporal Representation and Reasoning, 2002. TIME 2002. Proceedings.Ninth International Symposium on, Seite 20-27. (2002)
R. Brachman, und D. McGuinness. SIGIR '88: Proceedings of the 11th annual international ACM SIGIR conference on Research and development in information retrieval, Seite 161--174. New York, NY, USA, ACM, (1988)