1. Abrahamson K.R. Decidability and expressiveness of logics of processes Tech. Rep. 80-08-01, Univ. of Washington, 1980.
2. Barwise J. Axioms for abstract model theory Ann. Math. Logic 7, 1974, pp. 221–265.
3. Berman F. Models for verifiers Rep. of the Dept. of Comp. Sci., Purdue Univ. CSD-TR 343, 1980
4. Berman F., Peterson G.L. Expressiveness hierarchy for PDL with rich tests manuscript, Dept. of Comp. Sci., Univ. of Washington, 1978.
5. Ben-Ari M., Halpern J.Y., Pneuli A. Deterministic Propositional Dynamic Logic: finite models, complexity, completeness rep. of MIT, TM-190, 1981 (see also ICALP '81)