The Block Numerical Range of an n × n Block Operator Matrix. - Christiane Tretter; Markus Wagenhofer (SIAM J. Matrix Anal. Appl., 2003)

Eigenvalue enclosures and exclosures for non-self-adjoint problems in hydrodynamics. - B. Malcolm Brown; Matthias Langer; Marco Marletta; Christiane Tretter; Markus Wagenhofer (LMS J. Comput. Math., 2010)