1. Bergmann, M., Herbst, I., von Wieding, R., Wolter, F.E.: Haptical rendering of rough surfaces using their fractal dimension. In: Proceedings of the First PHANToM Users Research Symposium, pp. 9–12. German Cancer Research Center, Heidelberg, Germany (1999)
2. Bernstein, L.E., Eberhardt, S.P., Demorest, M.E.: Single-channel vibrotactile supplements to visual perception of intonation and stress. J. Acoust. Soc. Am. 85, 397–405 (1989)
3. Bolanowski, S.J., Gescheider, G.A., Verillo, R.T., Checkowsky, C.M.: Four channels mediate the mechanical aspects of touch. J. Acoust. Soc. Am. 84, 1680–1694 (1988)
4. Cornsweet, T.N.: Visual Perception. Academic Press, New York (1970)
5. Falconer, K.J.: Fractal geometry: mathematical foundations and applications. Wiley, Chichester (1990)