GIERTZ, M. A Note on a Problem of Busemann. MATHEMATICA SCANDINAVICA, [S. l.], v. 25, p. 145–148, 1969. DOI: 10.7146/math.scand.a-10951. Disponível em: https://www.mscand.dk/article/view/10951. Acesso em: 2 may. 2024.