1 Jan 2001 / An earlier version published in Proceedings of the 11th International Conference on General Relativity and Gravitation, ed. M. A. H. MacCallum, Cambridge University Press, Cambridge 1987, pp. 130-157
3 Dec 2004 / in The magnetized plasma in galaxy evolution, ed. K.T. Chyzy, K. Otmianowska-Mazur, M. Soida, and R.-J. Dettmar, Jagiellonian University, pp. 139-146 (2005)