SOBCZYK, Andrew. The Obliquity-Type of a Set of Vectors. Mathematica Scandinavica, Berkeley, CA, United States, v. 21, p. 195–198, 1967. DOI: 10.7146/math.scand.a-10859. Disponível em: https://journals.msp.org/mscand/article/view/2467. Acesso em: 25 jul. 2026.