Halic, G. “On a Representation of the Expansion Coefficients of a Function Relative to a Power Scale”. Rev. Anal. Numér. Théor. Approx., vol. 26, no. 1, Aug. 1997, pp. 85-89, https://ictp.acad.ro/jnaat/journal/article/view/1997-vol26-nos1-2-art11.