Thomas Eiter, Georg Gottlob, Thomas Schwentick. Second-Order Logic over Strings: Regular and Non-regular Fragments. In Werner Kuich, Grzegorz Rozenberg, Arto Salomaa, editors, Developments in Language Theory, 5th International Conference, DLT 2001, Vienna, Austria, July 16-21, 2001, Revised Papers. Volume 2295 of Lecture Notes in Computer Science, pages 37-56, Springer, 2001. [doi]
Abstract is missing.