F. Gers, J. Schmidhuber, and F. Cummins. Neural Nets, WIRN Vietri-99, Proceedings 11th Workshop on Neural Nets, Vietri sul Mare, Salerno, Italy, 20-22 May 1999, page 133--138. Vietri sul Mare, Italy, Springer Verlag, Berlin, (1999)
K. Rybicka, N. Schraudolph, and J. Schmidhuber. Lecture Notes on Comp. Sci. 2130, Proc. Intl. Conf. on Artificial Neural Networks (ICANN-2001), page 684--691. Springer: Berlin, Heidelberg, (2001)