H. K. Du and J. Pan, “Perturbation of Spectrums of 2 × 2 Operator Matrices,” Proceedings of the American Mathematical Society, Vol. 121, 1994, pp. 761-766.
http://dx.doi.org/10.1090/S0002-9939-1994-1185266-2

has been cited by the following article:

• TITLE: Spectra of 2 × 2 Upper-Triangular Operator Matrices

  AUTHORS: Haiyan Zhang

  KEYWORDS: Spectra; Upper-Triangular Operator Matrix; Fredholm Operator

  JOURNAL NAME: Applied Mathematics, Vol.4 No.11A, October 31, 2013

  ABSTRACT: In [Perturbation of Spectrums of 2 × 2 Operator Matrices, Proceedings of the American Mathematical Society, Vol. 121, 1994], the authors asked whether there was an operator such that for a given pair(A,B)of operators, where the operator was defined by . In this note, a partial answer for the question is given.