Frequency-domain criteria for gradient-like behavior of phase control systems with vector nonlinearities. - Aleksey Perkin; Vera Smirnova; Alexander Shepeljavyi (CCA/ISIC, 2009)

Asymptotic estimates for gradient-like distributed parameter systems with periodic nonlinearities. - Aleksey Perkin; Anton V. Proskurnikov; Vera Smirnova (ISIC, 2014)