J. Paakki. Programming Language Implementation and Logic Programming (PLILP
'93), volume 528 of Lect. Notes in Comp. Sci., page 243--254. Passau Germany, Springer-Verlag, (1991)
E. Duris. Proc.of the International Conference on Functional Programming (ICFP'97)
-- Poster Session, Amsterdam, The Netherlands, ACM Press, (June 1997)
P. Deransart, and J. Maluszynski. Journal of Logic Programming, 2 (2):
119--155(1985)Also published as a report, Linköping Institute of Technology
(October 1984), and as rapport RR 393, INRIA, Rocquencourt (1985)..