@article{Łenski:2011,
  author  = "W. Łenski and B. Szal",
  title   = "Approximation of integrable functions by general linear operators of their Fourier series at the Lebesgue points",
  journal = "Acta Mathematica Hungarica",
  volume  = "Vol. 131",
  number  = "no 4",
  pages   = "380--394",
  year    = "2011",
}