PEDERSEN, S.; WANG, Y. Universal spectra, universal tiling sets and the spectral set conjecture. MATHEMATICA SCANDINAVICA, [S. l.], v. 88, n. 2, p. 246–256, 2001. DOI: 10.7146/math.scand.a-14325. Disponível em: https://www.mscand.dk/article/view/14325. Acesso em: 28 apr. 2024.