1. A general approach to solving a wide class of fuzzy optimization problems;Ekel;Fuzzy sets, and Systems,1998
2. Fuzzy Set Theory and Its Application;Zimmermann,1990
3. An Introduction to Fuzzy Sets: Analysis and Design;Pedrycz,1998
4. Taking into account the uncertainty factor in problems of modelling and optimizing complex systems;Ekel;Advances in Modelling and Analysis,1994
5. Methods of decision making in fuzzy environment and their applications (invited 45 min. lecture);Ekel;Nonlinear Analysis: Theory, Methods and Applications,2001