中国科学院数学与系统科学研究院期刊网
The Solvability of Operator Equation AX - XA = C with Unbounded Operator A
Gen Qi XU,De Xing FENG
Acta Mathematica Sinica, Chinese Series . 2000, (2): 375 -384 .  DOI: 10.12386/A2000sxxb0050