PETUNIN, Yu. I.; TUPKO, N. P. Theory of quadratic estimates of variance. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 51, n. 9, p. 1217–1231, 1999. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4718. Acesso em: 14 apr. 2025.