1. S. E. Miller, collection: Waveguide Transmission Lines with Low Losses [Russian translation], IL, Moscow, p. 139, 1960.
2. G. S. Gorelik, Oscillations and Waves [in Russian], Fizmatgiz, Moscow, chapt. 9, 1959.
3. B. Z. Katsenelenbaum, The Theory of Nonuniform Waveguides with Slowly Varying Parameters [in Russian], izd. AN SSSR, Moscow, section, 6, 1961.
4. L. A. Vainshtein, Electromagnetic Waves [in Russian], izd. Sov. radio, Moscow, section 82, 1957.
5. V. V. Malin, Radiotekhnika i Élektronika,7, no. 8, 1349, 1962.