Sutton, D.R. and King, Peter J.H. (1995) Incomplete information and the functional data model. The Computer Journal 38 (1), pp. 31-42. ISSN 0010-4620.

Sutton, D.R. and King, Peter J.H. (1992) Integration of modal logic and the functional data model. In: Gray, P.M.D. and Lucas, R.J. (eds.) Advanced Database Systems, 10th British National Conference on Databases: BNCOD 10. Lecture Notes in Computer Science 618. Springer, pp. 156-174. ISBN 9783540556930.