lazy lambda calculus references

Speaking of ``lazy'' lambda calculus, I should add the following
references, the first of which offered the original formulation of the
issues.

S. Abramsky. Domain Theory and the Logic of Observable Properties.
Chapter 6, Ph.D. thesis, Imperial College, U. London, Oct. 1987.

S. Abramsky.  The lazy lambda-calculus.  In D. Turner, editor, Declarative
Programming, Academic Press, 1990. To appear.

S. Abramsky and C. L. Ong. Full abstraction in the lazy lambda calculus.
Information and Computation, 1989. Submitted.