中国科学院数学与系统科学研究院期刊网
A Remark on Lower Bound of the Ratio of ||f-Sn(f)||/En(f)
Xu Dong LIN
Acta Mathematica Sinica, Chinese Series . 2005, (3): 573 -576 .  DOI: 10.12386/A2005sxxb0069