1. In erpolation theorems for program schemata;Abramson;Information and Control,1978
2. On the power of non-determinism in dynamic logic;Berman,1982
3. Characterization of acceptable by Algol-like programming languages.;Crasemann,1983
4. Engeler, E. [1975], “Algorithmic logic,” in Mathematical Center Tract No. 63, edited by de Bakker, Amsterdam.
5. Erimbetov, M.M. [1981], “On the expressive power of programming logics,”Proceedings of the Conference; Research in Theoretical Programming, Alma-Alta 1981, 49-68 (in Russian).