Rudolf Berghammer, Bernhard Möller, Georg Struth: Relational and Kleene-Algebraic Methods in Computer Science: 7th International Seminar on Relational Methods in Computer Science and 2nd International Workshop on Applications of Kleene Algebra, Bad Malente, Germany, May 12-17, 2003, Revised Selected Papers. Lecture Notes in Computer Science 3051, Springer 2004, ISBN 3-540-22145-X