中国科学院数学与系统科学研究院期刊网
The Reduction Square Root and Perturbation for a Class of Strongly Continuous Operator Families
Chuang CHEN, Xiao Qiu SONG, Hui Min LI
Acta Mathematica Sinica . 2010, (10): 1993 -2002 .  DOI: 10.1007/s10114-010-7644-3