@BOOK { Rsds2346,
author = {Polkowski, Lech T.},
title = {Rough Sets: Mathematical Foundations},
series = = {Advances in Soft Computing},
publisher = {Springer-Verlag},
address = {Heidelberg - Berlin, Germany},
year = 2002,
url = {http://www.springer.de},
isbn = {3-7908-1510-1},
keywords = {fuzzy set theory, fuzzy sets, mathematical foundations, rough sets, rough sets theory (RST), },
}