Kirane, M. y Qafsaoui, M. (2002): «On the asymptotic behavior for convection-diffusion equations associated to higher order elliptic operators in divergence form», Revista Matemática Complutense, 15(2), pp. 585–598. doi: https://doi.org/10.5209/rev_REMA.2002.v15.n2.16930.