Positive and negative approximate controllability results for semilinear parabolic equations. J. J. Díaz; A. M. Ramos — 1995 Revista de la Real Academia de Ciencias Exactas Físicas y Naturales
Approximation of the three-field Stokes system via optimized quadrilateral finite elements V. Ruas; J. H. Carneiro de Araújo; M. A. M. Silva Ramos — 1993 ESAIM: Mathematical Modelling and Numerical Analysis - Modélisation Mathématique et Analyse Numérique