with Prokopowicz, P. , Kacprzak, D. , 2009, Fuzziness – representation of dynamic changes by ordered fuzzy numbers, in R. Seising (ed.), Views on fuzzy sets and systems from different perspectives, Dordrecht, Springer, pp. 485-508.
with Starosta, B. , 2009a, Meta sets – another approach to fuzziness, in R. Seising (ed.), Views on fuzzy sets and systems from different perspectives, Dordrecht, Springer, pp. 509-532.