Badalyan, H. V. “ON A SYSTEM OF FUNCTIONS GENERATING CLASSICAL ORTHOGONAL SYSTEMS OF ALGEBRAIC POLYNOMIALS”. Proceedings of the YSU A: Physical and Mathematical Sciences, vol. 34, no. 1 (192), Apr. 2000, pp. 3-9, https://doi.org/10.46991/PYSUA.2000.34.1.003.