Bruce W. Ballard John C. Lusth Nancy L. Tinkham LDC-1: A Transportable, Knowledge-Based Natural Language Processor for Office Environments. 1-25 1984 2 ACM Trans. Inf. Syst. 1 db/journals/tois/tois2.html#BallardLT84 http://doi.acm.org/10.1145/357417.357418