Comment on: “An observation on the periodic solutions to nonlinear physical models by means of the auxiliary equation with a sixth-degree nonlinear term” [Commun Nonlinear Sci Numer Simulat 2013;18:2177–2187]

This article shows that all novel exact solutions in the commented paper are not admitted by the original generalized Klein–Gordon equation and active-dissipative dispersive media equation. In addition, we present general solutions of certain auxiliary equation with sixth-degree nonlinear term. Then, based on above general solutions, we find that five cases in their Table 1 is shown to be incorrect.