Anne Brüggemann-Klein, Rolf Klein. On the Minimality of ::::K::::, ::::F:::: and ::::D:::: or: Why Löten is Non-Trivial. In Egon Börger, editor, Computation Theory and Logic, In Memory of Dieter Rödding. Volume 270 of Lecture Notes in Computer Science, pages 59-66, Springer, 1987.
Abstract is missing.