K. Wolff. Computing Anticipatory Systems. CASYS'99 - Third International Conference, Liège, Belgium, 1999, 517, page 83-97. American Institute of Physics, Conference Proceedings, (2000)
K. Wolff. Proceedings of the 10th International Conference on Conceptual Structures (ICCS 2002), volume 2393 of Lecture Notes in Computer Science, page 341-353. Springer, (2002)