On the ellipticity and solvability of an abstract second-order differential equation. El Haial, Abdelillah; Labbas, Rabah — 2001 Electronic Journal of Differential Equations (EJDE) [electronic only]
An L p -approach for the study of degenerate parabolic equations. Labbas, Rabah; Medeghri, Ahmed; Sadallah, Boubaker-Khaled — 2005 Electronic Journal of Differential Equations (EJDE) [electronic only]
Study of the limit of transmission problems in a thin layer by the sum theory of linear operators. Angelo Favini; Rabah Labbas; Keddour Lemrabet; Stéphane Maingot — 2005 Revista Matemática Complutense
Study of a complete abstract differential equation of elliptic type with variable operator coefficients, I. Angelo Favini; Rabah Labbas; Keddour Lemrabet; Boubaker-Khaled Sadallah — 2008 Revista Matemática Complutense