CLARK, Benjamin; PAPARELLA, Pietro. Polynomials that Preserve Nonnegative Matrices of Order Two. Mathematics Exchange, [S. l.], v. 16, n. 1, p. 58–65, 2026. DOI: 10.33043/AM5MAEyBVA. Disponível em: https://openjournals.bsu.edu/mathexchange/article/view/6182. Acesso em: 28 apr. 2026.