Poznan University of Technology - Institute of Mathematics.

Polish Academy of Sciences - Institute of Mathematics.

Jagiellonian University, Kraków - Institute of Mathematics.

Nicholas Copernicus University, Torun - Faculty of Mathematics and Computer Science.

University of Lódz - Faculty of Mathematics.

Adam Mickiewicz University - Mathematics and Computer Science. (Poznañ, Poland)

Maria Curie-Sklodowska University (UMCS), Lublin - Faculty of Mathematics and Physics.

Warsaw University of Technology - Faculty of Mathematics and Computer Science.

Wroclaw University of Technology - Institute of Mathematics.

University of Warsaw - Institute of Mathematics.

Wroclaw University - Institute of Mathematics.