KARPENKOV, O. Elementary notions of lattice trigonometry. MATHEMATICA SCANDINAVICA, [S. l.], v. 102, n. 2, p. 161–205, 2008. DOI: 10.7146/math.scand.a-15058. Disponível em: https://www.mscand.dk/article/view/15058. Acesso em: 11 apr. 2025.