中国科学院数学与系统科学研究院期刊网
AMS
Generalized I-Contractions and Pointwise R-Subweakly Commuting Maps
D. O'REGAN, N. HUSSAIN
Acta Mathematica Sinica . 2007, (8): 1505 -1508 .  DOI: 10.1007/s10114-007-0935-7