References
- Machigan Math. J. v.32 The reduced minimum modules C. Apostol
- Proc. Amer. Math. Soc. v.121 Perturbation of spectrums of 2×2 operator matrices H. K. Du;P. Jin
- Unbonunded Linear Operators S. Goldberg
- Proc. Amer. Math. Soc. v.128 Invertible completions of 2×2 upper triangular matrics J. K. Han;H. Y. Lee;W. Y. Lee
- Invertibility and Singularity for Bounded Linear Operators R. E. Harte
- Int. Eq. Op. Th. v.22 Norm inequalities of positive operator matrices J. C. Hou;H. K. Du
- Perturbation theory for linear operators T. Kato