Periodic solutions for some phi-Laplacian and reflection equations
  This work is devoted to the study of the existence and periodicity of solutions of initial differential problems, paying special attention to the explicit computation of the period. These problems are also connected with some particular initial and boundary value problems with reflection, which allows us to prove existence of solutions of the latter using the existence of the first. 
Alberto Cabada, and F. Adri\'an F. Tojo
math.CA