Derkach, V., Hassi, S. & de Snoo, H., 2006, Operator Theory in Krein Spaces and Nonlinear Eigenvalue Problems. Forster, K., Jonas, P. & Langer, H. (uitgave). BASEL: Birkhauser, blz. 117-13317 blz. (OPERATOR THEORY : ADVANCES AND APPLICATIONS; vol. 162).