AGRATINI, O. 2019. Book reviews: “Vijay Gupta, Michael Th. Rassias,” Moments of Linear Positive Operators and Approximation, Springer, 2019, viii + 96 p., ISBN 978-3-030-19454-3; 978-3-030-19455-0 (ebook). Studia Universitatis Babeș-Bolyai Mathematica. 64, 4 (Dec. 2019), 601.