“…The method of determination of a Lyapunov functional for a time delay system with one delay was presented by Repin [15]. Duda [3] used the Repin's method to determination of a Lyapunov functional for a system with two delays, for a system with both lumped and distributed delay [5,10], for a system with time-varying delay [6,8]. In last years a method of determination of a Lyapunov functional by means of Lyapunov matrices is very popular, see for example [9,12,13,14,16].…”