1. Akama, S., Murai, T., Kudo, Y.: Reasoning with Rough Sets. Springer, Heidelberg (2018)
2. Chellas, B.: Modal Logic: An Introduction. Cambridge University Press, Cambridge (1980)
3. Lin, T.Y.: Granular computing on binary relation, I data mining and neighborhood systems, II rough set representations and belief functions. In: L. Polkowski, A. Skowron (eds.) Rough Sets in Knowledge Discovery 1: Methodology and Applications, pp. 107–121, 122–140. Physica-Verlag, Heidelberg (1998)
4. Murai, T., Nakata, M., Sato, Y.: A note on filtration and granular reasoning. Terano, T. et al. (eds.) New Frontiers in Artificial Intelligence, LNAI 2253, pp. 385–389. Springer (2001)
5. Murai, T., Resconi, G., Nakata, M., Sato, Y.: Operations of zooming in and out on possible worlds for semantic fields. In: Damiani, E. et al. (eds.) Knowledge-Based Intelligent Information Engineering Systems and Allied Technologies, pp. 1083–1087 (2002)