Casas, Eduardo, y Alberto Fernández. «Optimal Control of Quasilinear Elliptic Equations With Non Dilferentiable Coefficients at the Origin». Revista Matemática Complutense 4, no. 2 (enero 1, 1991): 227. https://doi.org/10.5209/rev_REMA.1991.v4.n2.17974.