Proceedings of ECOpole
Proceedings of ECOpole > 2013 > Vol. 7, No. 2 > 567--573
Proceedings of ECOpole > 2013 > Vol. 7, No. 2 > 601--607
Proceedings of ECOpole > 2013 > Vol. 7, No. 2 > 567--573
Proceedings of ECOpole > 2013 > Vol. 7, No. 2 > 601--607