We investigate the existence and multiplicity of periodic solutions for a class of second-order differential systems with impulses. By using variational methods and critical point theory, we obtain such a system possesses at least one nonzero, two nonzero, or infinitely many periodic solutions generated by impulses under different conditions, respectively. Recent results in the literature are generalized and significantly improved.
Liu Yang. Haibo Chen. "Existence and Multiplicity of Periodic Solutions Generated by Impulses." Abstr. Appl. Anal. 2011 1 - 15, 2011. https://doi.org/10.1155/2011/310957