Serge Gaspers, Sebastian Ordyniak, M. S. Ramanujan, Saket Saurabh, Stefan Szeider. Backdoors to q-Horn. 30th International Symposium on Theoretical Aspects of Computer Science, STACS 2013, February 27 - March 2, 2013, Kiel, Germany (Natacha Portier and Thomas Wilke), volume 20 of LIPIcs, pages 67-79, 2013, Leibniz-Zentrum fuer Informatik.