中国科学院数学与系统科学研究院期刊网
The Point, Residual and Continuous Spectrum of 3×3 Upper Triangular Operator Matrices
Xiu Feng WU, Jun Jie HUANG
Acta Mathematica Sinica, Chinese Series . 2019, (6): 817 -832 .  DOI: 10.12386/A2019sxxb0075