中国科学院数学与系统科学研究院期刊网
AMS
Approximation of Integrable Functions by General Linear Operators of Their Fourier Series
Włodzimierz ŁENSKI, Bogdan SZAL
Acta Mathematica Sinica . 2012, (6): 1119 -1134 .  DOI: 10.1007/s10114-011-0568-8