Zapryanova, T., Souroujon, D. (2019) Characterization of Best Algebraic Approximation by a Generalized Modulus of Smoothness, Melville, NY: AIP [American Institute of Physics] Publ. pp. 060001-1 - 060001-8 (AIP Conf. Proc., 2172), ISBN 978-0-7354-1919-3 ; ISSN 0094-243X.