Drewes, Frank, Annegret Habel, Berthold Hoffmann, and Detlef Plump. 2010. “Manipulation of Graphs, Algebras and Pictures. Essays Dedicated to Hans-Jörg Kreowski on the Occasion of His 60th Birthday”. Electronic Communications of the EASST 26 (April). https://doi.org/10.14279/tuj.eceasst.26.369.