Proceedings of ECOpole
Proceedings of ECOpole > 2015 > Vol. 9, No. 2 > 777-783
Proceedings of ECOpole > 2015 > Vol. 9, No. 2 > 581--587
Proceedings of ECOpole > 2015 > Vol. 9, No. 2 > 615--625
Proceedings of ECOpole > 2015 > Vol. 9, No. 2 > 397--404