1. D. Scheingold (editor), Handbook on Nonlinear Circuits [Russian translation], Mir, Moscow (1977).
2. N. V. Gurevich, Synthesis of Parametric Functional Transducers [in Russian], Svyaz', Moscow (1978).
3. P. Richman and N. Walker, IEEE Trans. on Instr. and Measur.,20, 313 (1971).
4. J. R. Pickering, US Patent No. 3628160 (1971).