1. Attia, A.: 2002, Ph.D. thesis, Department of Control Engineering, Faculty of Electrical Engineering, Czech Technical University, Prague, Czech Republic.
2. Attia, A. and Horáček, P.: 2001, Acta polytechnika J., CVUT. 6, 69.
3. Badalyan, O. G., Obridko, V. N., and Sýkora, J.: 2001, Solar Phys. 199, 421.
4. Bounar, K. H., Cliver, E. W., and Boriakoff, V.: 1997a, Solar Phys. 176, 221.
5. Bounar, K. H., Cliver E. W., and Boriakoff, V.: 1997b, Solar Phys. 176, 211.