DIAM II: The binary infological level and its database language - FORALMichael E. Senko1976Conference on Data 1976Conference paper
High level domain definition in a relational date base systemDennis J. McLeod1976Conference on Data 1976Conference paper
A high-level data manipulation language for hierarchical data structuresBarron C. HouselNan C. Shu1976Conference on Data 1976Conference paper