K. BOYADZHIEV; VICTOR H. MOLL. The integrals in Gradshteyn and Ryzhik Part 26: The exponential integral. Scientia Series A: Mathematical Sciences, [S. l.], v. 26, p. 19–30, 2015. Disponível em: https://revistas.usm.cl/scientia/article/view/225.. Acesso em: 28 jun. 2025.