A characterization for the spectral capacity of a finite system of operators Ştefan Frunză (1977) Czechoslovak Mathematical Journal
A characterization of some subsets of S-essential spectra of a multivalued linear operator Teresa Álvarez, Aymen Ammar, Aref Jeribi (2014) Colloquium Mathematicae We characterize some S-essential spectra of a closed linear relation in terms of certain linear relations of semi-Fredholm type.