“…The nonlinear partial differential equations (PDEs for short) have proved to be valuable tools for the modeling of many physical, chemical and biological phenomena, see for instance [27,32,34] and references therein. In the last few decays, there has been a noticeable interest on the study of existence of solution to nonlinear elliptic systems, especially when the nonlinear term appears as a source in the equation with the Dirichlet's or Neumann's boundary conditions, see for instance [13,28,32] and references therein. Nonlinear systems are divided into two broad classes, first one is with a variational structure, namely Hamiltonian or gradients systems, see for instance [1,16,18] and second one is the class of non-variational problems, which can be maintained through the topological methods (fixed-point arguments), see for instance [2,4,9,10].…”