Note on KKM maps and applications. Chen, Y.Q.; Cho, Y.J.; Kim, J.K.; Lee, B.S. — 2006 Fixed Point Theory and Applications [electronic only]
Antiperiodic boundary value problems for finite dimensional differential systems. Chen, Y.Q.; O'Regan, D.; Wang, F.L.; Zhou, S.L. — 2009 Boundary Value Problems [electronic only]