1. S. Abramsky. Observation equivalence as a testing equivalence. Theor. Comp. Sci.53, pp 225–241, 1987.
2. N. Akinaga, Decision Procedures for Relations on Probabilistic Transition Systems. MSc thesis, Department of Computer Systems, Uppsala University, Uppsala, Sweden, 1989. Available as report DoCS 89/19.
3. J.A. Bergstra, J.W. Klop. Process algebra for synchronous communication. Information and Control60, pp 109–137, 1984.
4. G. Berry, P.-L. Curien, J.-J. Lévy. Full abstraction for sequential languages: the state of the art. Algebraic Methods in Semantics, eds. M. Nivat and J.C. Reynolds, Cambridge University Press, pp 89–132, 1985.
5. I. Christoff. Distinguishing probabilistic processes through testing. Manuscript presented at Nordic Workshop on Program Correctness, Uppsala, Sweden, 1989.