COHEN, E. L. The Diophantine equation $x^2+11=3^k$ and related questions. MATHEMATICA SCANDINAVICA, [S. l.], v. 38, p. 240–246, 1976. DOI: 10.7146/math.scand.a-11631. Disponível em: https://www.mscand.dk/article/view/11631. Acesso em: 2 may. 2024.