1. On the Browder essential spectrum of a linear relation;Alvarez;Publ Math Debrecen,2008
2. Small perturbation of normally solvable relations;Alvarez;Publ Math Debrecen,2012
3. Essential descent spectrum and commuting compact perturbations;Fredj;Extracta Mathematicae,2006
4. The descent spectrum and perturbations;Burgos;J Operator Theory,2006
5. Multivalued Operators and Boundary Value Problems. Lecture Notes in Math 183;Coddington,1971