On the existence of periodic solutions for a class of generalized forced Liénard equations

In this work the second-order generalized forced Liénard equation x″+(f(x)+k(x)x′)x′+g(x)=p(t)x″+(f(x)+k(x)x′)x′+g(x)=p(t) is considered and a new condition for guaranteeing the existence of at least one periodic solution for this equation is given.