“…The sublinear nonlinearity u q with 0 < q < 1 appearing in (1.1) induces the absorption effect on ∂Ω. Sublinear boundary conditions were explored in [12,10,27,11,5,19,22]. The case of sublinear incoming flux on ∂Ω, the mixed case of sublinear absorption, and incoming flux on ∂Ω, and the sublinear nonlinear term u q multiplied by indefinite weight were studied in [12,27,11], in [10], and in [5,19,22], respectively.…”