Lupaş, Luciana. “ An Identity for Ultraspherical Polynomials”. Rev. Anal. Numér. Théor. Approx. 24, no. 1 (August 1, 1995): 181–185. Accessed April 17, 2025. https://ictp.acad.ro/jnaat/journal/article/view/1995-vol24-nos1-2-art19.