BERGKVIST, T.; RULLGÅRD, H.; SHAPIRO, B. On Bochner-Krall orthogonal polynomial systems. MATHEMATICA SCANDINAVICA, [S. l.], v. 94, n. 1, p. 148–154, 2004. DOI: 10.7146/math.scand.a-14434. Disponível em: https://www.mscand.dk/article/view/14434. Acesso em: 6 may. 2024.