1. V. Brattka, Some notes on fine computability, unpublished note.
2. Y. Endo, Walsh Analysis, Tokyo Denki Univ. Press, Tokyo, 1993. (in Japanese).
3. On the Walsh functions;Fine;Trans. Amer. Math. Soc.,1949
4. The generalized Walsh functions;Fine;Trans. Amer. Math. Soc.,1950
5. Walsh series and transforms;Golubov,1987