1. S. Abiteboul and N. Bidoit. Non First Normal Form Relations: an Algebra Allowing Data Restructuring. Journal of Computer and System Sciences, 1986.
2. F. Bancilhon, S. Cluet, and C. Delobel. A Query Language for an Object-Oriented Database System. In 2nd Int. Worshop on Database Programming Languages (DBPL), pages 301–322, 1989.
3. B. P. Buttenfield and J. Delotto. Multiple Representation: Report on the Specialist Meeting. Technical Report 89-3, National Center for Geographic Information and Analysis, Santa Barbara, 1989.
4. F. Bancilhon, C. Delobel, and P. Kannelakis, editors. The O 2 Book. Morgan Kaufmann, 1991.
5. B.P. Buttenfield and R. P. McMaster. Map Generalization: Making Rules for Knowledge Representation. Longman Scientific&Technical, New-York, 1991.