1. M. I. Bukatar’ and E. F. Tsar’kov, “Self-oscillations in a vacuum tube oscillator with delayed feedback,” Izvestiya Vuzov, No. 8, 1117–1125 (1970).
2. I. S. Gonorovskii, “To the theory of high-frequency oscillators with delayed feedback,” Radiotekhnika, 13, No. 5, 19–30 (1958).
3. R. A. Stratonovich, Selected Issues from the Theory of Fluctuations in Radio Engineering [in Russian], Sov. Radio, Moscow (1961).
4. E. F. Tsar’kov, Random Perturbations of Functional Differential Equations [in Russian], Zinatne, Riga (1989).
5. V. P. Rubanik, Oscillations of Quasilinear Systems with Delay [in Russian], Nauka, Moscow (1969).