Proceedings of ECOpole
Proceedings of ECOpole > 2007 > Vol. 1, No. 1/2 > 221--225
Proceedings of ECOpole > 2007 > Vol. 1, No. 1/2 > 153--157
Proceedings of ECOpole > 2007 > Vol. 1, No. 1/2 > 221--225
Proceedings of ECOpole > 2007 > Vol. 1, No. 1/2 > 153--157