Krech, G., & Wachnicki, E. (2013). Approximation by some combinations of the Poisson integrals for Hermite and Laguerre expansions. Annales Universitatis Paedagogicae Cracoviensis Studia Mathematica, 12, 21–29. Retrieved from https://studmath.uken.krakow.pl/article/view/13182