Masami Ito, Kayoko Shikishima-Tsuji. Some Results on Directable Automata. In Juhani Karhumäki, Hermann A. Maurer, Gheorghe Paun, Grzegorz Rozenberg, editors, Theory Is Forever, Essays Dedicated to Arto Salomaa on the Occasion of His 70th Birthday. Volume 3113 of Lecture Notes in Computer Science, pages 125-133, Springer, 2004. [doi]
Abstract is missing.