1. M. Baaz, R. Zach, Short proofs of tautologies using the schema of equivalence, in: Computer Science Logic: Seventh Workshop, CSL’93, Lecture Notes in Computer Science, Vol. 832, eds. E. Borger, Y. Gurevich, K. Meinke. Springer, Berlin, 1994, pp. 33–35.
2. Dijkstra–Scholten predicate calculus;Bijlsma;Acta Informatica,1998
3. Predicate Calculus and Program Semantics;Dijkstra,1990
4. The Science of Programming;Gries,1981
5. A logical approach to discrete math;Gries,1993