1. D. G. Kiely, Dielectric Aerials, Methuen and Co., London (1953).
2. L. A. Vainshtein, Electromagnetic Waves [in Russian], Sov. Radio, Moscow (1957).
3. B. Z. Katsenelenbaum, High-Frequency Electrodynamics [in Russian],Nauka, Moscow (1966).
4. L. A. Vainshtein, Open Cavities and Waveguides [in Russian], Sov. Radio, Moscow (1966).
5. J. Arnbak, Electron. Lett.,5, No. 3, 41 (1969).