1. Bazan J., Skowron A., Synak P.: Market data analysis: A rough set approach, ICS Research Report 6/94 Warsaw University of Technology 1994.
2. Brown, E.M.: Boolean reasoning. Dordrecht: Kluwer 1990.
3. Market data, Hughes Research Laboratories, manuscript.
4. International Workshop Rough Sets: State of the Art and Perspectives, Poznan — Kiekrz (Poland), September 2–4, 1992. Extended Abstracts. Poznan 1992. Full papers in Foundations of Computing and Decision Sciences, Vol.18, No 3–4 (1993).
5. Kodratoff Y., Michalski R.(eds.): Machine Learning vol III, Morgan Kaufmann, San Mateo, CA, 1990.