Steigman, Gary (1969). "Antimatter, Galactic Nuclei and Theories of the Universe: Antimatter and Cosmology". Nature224 (5218): 477–481. doi:10.1038/224477b0. Bibcode: 1969Natur.224..477S.
Steigman, Gary; Schramm, David N.; Gunn, James E. (January 17, 1977). "Cosmological limits to the number of massive leptons". Physics Letters B66 (2): 202–204. doi:10.1016/0370-2693(77)90176-9. Bibcode: 1977PhLB...66..202S.
Steigman, Gary (1969). "Antimatter, Galactic Nuclei and Theories of the Universe: Antimatter and Cosmology". Nature224 (5218): 477–481. doi:10.1038/224477b0. Bibcode: 1969Natur.224..477S.
Steigman, Gary; Schramm, David N.; Gunn, James E. (January 17, 1977). "Cosmological limits to the number of massive leptons". Physics Letters B66 (2): 202–204. doi:10.1016/0370-2693(77)90176-9. Bibcode: 1977PhLB...66..202S.