1. Green BF, Wolf AK, Chomsky C, and Laughery K. Baseball: An automatic question answerer. In Proceedings of Western Computing Conference, Vol. 19, 1961, pp. 219-224.
2. Weizenbaum J. ELIZA - a computer program for the study of natural language communication between man and machine. In Communications of the ACM, Vol. 9(1), 1966, pp. 36-45.
3. Woods W. Progress in Natural Language Understanding - An Application to Lunar Geology. In Proceedings of AFIPS Conference, Vol. 42, 1973, pp. 441-450.
4. Bobrow DG, Kaplan RM, Kay M, Norman DA, Thompson H, and Winograd T. Gus, a frame-driven dialog system. Artificial Intelligence, Vol. 8(2), 1977, pp. 155-173.
5. Katz B. Annotating the World Wide Web using natural language. In Proceedings of the 5th RIAO conference on Computer Assisted Information Searching on the Internet, 1997, pp. 136-159.