1. A calculus for recursive program schemes;de Bakker,1973
2. Generators for algebras of relations;Bednarek;Bull. Amer. Math. Soc.,1976
3. Some remarks on relational composition in computational theory and practice;Bednarek,1977
4. Projective algebra and the calculus of relations;Bednarek;J. Symbolic Logic,1978
5. Über eine natürliche Erweiterung des Relationenkalküls;Bernays,1959