1. J. Nührenberg and R. Zille, Phys. Lett. A 129, 113 (1988).
2. J. Nührenberg, W. Lotz, and S. Gori, in Proceedings of the Joint Varenna—Lausanne International Workshop on Theory of Fusion Plasmas, Ed. by E. Sindoni and J. Vaclavik (Editrice Compositori, Bologna, 1994), p. 3.
3. D. A. Garren and A. H. Boozer, Phys. Fluids 3, 2805 (1991).
4. A. A. Galeev and R. Z. Sagdeev, Zh. Éksp. Teor. Fiz. 53, 348 (1967) [Sov. Phys. JETP 26, 233 (1968)].
5. W. Lotz and J. Nührenberg, Phys. Fluids 31, 2984 (1988).