PARANJPYE, R. P. The Foci of the General Conic. The Journal of the Indian Mathematical Society, [S. l.], v. 3, n. 2, p. 77–78, 1911. DOI: 10.18311/jims/1911/17819. Disponível em: http://informaticsjournals.com/index.php/jims/article/view/17819. Acesso em: 4 may. 2024.