Existence and multiplicity of solutions with prescribed period for a second order quasilinear O.D.E.

MANUEL A. DEL PINO School of Mathematics, University of Minnesota, Minneapolis, MN 55455, U.S.A. RAIL F. MANASEVICH Departamento de Matematicas, F.C.F.M., Universidad de Chile, Casilla 170, Correo 3, Santiago, Chile and ALEJANDRO E. MUR~A Division of Applied Mathematics, Brown University, Providence, RI 02912, U.S.A. (Received 20 September 1990; received for publication 13 March 1991)