1. N.F.Kovalev et al, Radio Physics and Quantum Electronics, No. 11, 1968, pp. 449–450.
2. B.Z. Katsenelenbaum, Theory of Nonuniform Waveguides with Slowly Varying Parameters, Moscow: Akad. Nauk SSSR, 1961. (in Russian)
3. J.M. Neilson et al, IEEE Trans. Microwave Theory Tech., Vol. MTT-37, 1989, pp. 1165–1169.
4. L.A. Vaynsteyn, Open Resonators and Open Waveguides, Golem Press, Boulder, Colorado, 1969.
5. B.Z.Katsenelenbaum et al, Radiotekhnika i Electronika, No. 12, 1967, pp.244–251. (in Russian)