PERLES, M. A.; SHEPARD, G. C. Angle Sums of Convex Polytopes. Mathematica Scandinavica, Berkeley, CA, United States, v. 21, p. 199–218, 1967. DOI: 10.7146/math.scand.a-10860. Disponível em: https://journals.msp.org/mscand/article/view/2466. Acesso em: 25 jul. 2026.