1. Stability and Asymptotic Behavior of Differential Equations (D. C. Heath, Boston, 1965).
2. and , Asymptotic Properties of Solutions of Nonautonomous Ordinary Differential Equations (Kluwer Academic Publishers, Dordrecht - Boston - London, 1993).
3. The oscillation character of the solutions of the equation $y\sp{(n)}+f(x)y\sp\alpha=0$, $n>1$