HELSØ, M.; RANESTAD, K. Rational quartic spectrahedra. MATHEMATICA SCANDINAVICA, [S. l.], v. 127, n. 1, p. 79–99, 2021. DOI: 10.7146/math.scand.a-121456. Disponível em: https://www.mscand.dk/article/view/121456. Acesso em: 16 may. 2021.