1. L. V. Kantorovich and V. I. Krylov, Approximate Methods of Higher Analysis [in Russian], Fizmatgiz, Moscow (1962).
2. V. L. Rrachev, Geometric Applications of Logic Algebra [in Russian], Tekhnika, Kiev (1967).
3. V. L. Rvachev, L. V. Kurpa, N. G. Sklepus, and L. A. Uchishvili, Method of R-Functions in Problems of Bending and Vibration of Plates of Complex Shape [in Russian], Naukova Dumka, Kiev (1973).
4. A. P. Filippov, Vibrations of Deformation Systems [in Russian], Mashinostroenie, Moscow (1970).
5. A. W. Leissa, Vibration of Plates. Sci. Tech. Inform. Div., Office of Technology Utilization, NASA, Washington (1969).