Proceedings of ECOpole
Proceedings of ECOpole > 2013 > Vol. 7, No. 2 > 765--771
Proceedings of ECOpole > 2013 > Vol. 7, No. 2 > 651--658
Proceedings of ECOpole > 2013 > Vol. 7, No. 2 > 765--771
Proceedings of ECOpole > 2013 > Vol. 7, No. 2 > 651--658