“…The existence and multiplicity of solutions for elliptic systems considered also in unbounded domains has been widely discussed by many authors for years (see, e.g., previous studies
3,13–21 and references therein). The results concerning the multiplicity of solutions for systems of similar form and their additional properties can be found, among others, in Conti et al
13 There, applying the variational approach, the authors proved the existence of at least nine solutions (not necessarily positive) in the case when
is a bounded and regular domain in
, the right‐hand side is a Carathéodory function and satisfies, among others, some growth conditions.…”