PageHeader : Funkcialaj Ekvacioj, 33 (1990) 19-38 Title : On a Dynamical System in the Lienard Plane. Title : Necessary and Sufficient Conditions for the Intersection Title : with the Vertical Isocline and Applications* AuthorInfo : By AuthorInfo : Gabriele VILLARI and Fabio ZANOLIN AuthorInfo : (University of Firenze and University of Udine, Italy) section : 1. Introduction section : 2. Intersection with the curve $y =F(x)$ section : 3. Periodic solutions of Lienard equation section : 4. The forced case section : References