ISNAINI, U. Beberapa Sifat Ideal Bersih-N. Jurnal Fourier, [S. l.], v. 5, n. 2, p. 65–70, 2016. DOI: 10.14421/fourier.2016.52.65-70. Disponível em: https://fourier.or.id/index.php/FOURIER/article/view/55. Acesso em: 3 jul. 2022.