1. R. A. Helliwell, in Modern Radio Science 1993, Ed. by H. Matsumoto (Oxford Univ. Press, New York, 1993), p. 189.
2. R. A. Helliwell, Whistlers and Related Ionospheric Phenomena (Dover, Mineola, 2006).
3. I. G. Kondrat’ev, A. V. Kudrin, and T. M. Zaboronkova, Electrodynamics of Density Ducts in Magnetized Plasmas (Gordon & Breach, Amsterdam, 1999).
4. Cs. Ferencz, O. E. Ferencz, D. Hamar, and J. Lichtenberger, Whistler Phenomena: Short Impulse Propagation (Kluwer, Dordrecht, 2001).
5. H. G. James, J. Geophys. Res. 111, A09315 (2006).