1. The Logic of Questions and Answers;Belnap,1977
2. The user interface in interactive systems;Bennett,1972
3. Construction and implementation of an information query language on the basis of the relational data base theory;Bjerre,1977
4. Relational completeness of data base languages;Cord,1972
5. Seven steps to RENDEZVOUS with the casual user;Cord;Data Base Management. North-Holland,1974