This paper is concerned with the following retarded Li'{e}nard equation $$x''(t)+f_1(x(t))(x'(t))^2+f_2(x(t))x'(t)+g_1(x(t))+g_2(x(t-au(t)))=e(t).$$ We prove a new theorem which ensures that all solutions of the above Li'{e}nard equation satisfying given initial conditions are bounded. As one will see, our results improve some earlier results even in the case of $f_1(x)equiv 0$.
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