(1)
Favini, A. .; Labbas, R. .; Lemrabet, K. .; Sadallah, B.-k. . Study of a Complete Abstract Differential Equation of Elliptic Type with Variable Operator Coefficients, I. Rev. mat. complut. 2008, 21 ,1, 89-133. https://doi.org/10.5209/rev_REMA.2008.v21.n1.16438.