1. Book, R.V., Jantzen, M., Wrathall, C.: Monadic Thue systems. Theoret. Comput. Sci. 19, 231?251 (1982)
2. Book, R.V., Otto, F.: String-Rewriting Systems. Texts Monogr. Comput. Sci. Springer-Verlag, New York, 1993
3. Chidlovskii, B.: Using regular tree automata as XML schemas. In: J. Hoppenbrouwers, T. de Souza Lima, M. Papazoglou, A. Sheth (eds.), Proc. IEEE Advances in Digital Libraries ADL-00, IEEE Comput. Society, 2000, pp. 89?98
4. Choffrut, C., Karhumäki, J.: Combinatorics of words. In: G. Rozenberg, A. Salomaa (eds.), Handbook of Formal Languages. Vol. 1, Springer-Verlag, 1998, pp. 329?438
5. Coquand, T., Persson, H.: A proof-theoretical investigation of Zantema?s problem. In: M. Nielsen, W. Thomas (eds.), Proc. 11th Annual Conf. of the EACSL CSL-97. Lecture Notes in Comput. Sci. Vol. 1414, Springer-Verlag, 1998, pp. 177?188