中国科学院数学与系统科学研究院期刊网
Fredholm Perturbation of Spectra of 2 × 2-Upper Triangular Matrices
Shi Fang ZHANG, Huai Jie ZHONG, Jun De WU
Acta Mathematica Sinica, Chinese Series . 2011, (4): 581 -590 .  DOI: 10.12386/A2011sxxb0059