1Alpher R A, Gamow G, Herman R. Thermal cosmic radiation and the formation of protogalaxies. Proceedings of the National Academy of Sciences of the United States of America, 1967, 58(6): 2179.
2Penzias A A, Wilson R W. A measurement of excess antenna temperature at 4080 Mc/s. Astrophysical Journol, 1965, 142: 419.
3Mather J C, Cheng E S, Eplee R E Jr, et al. A preliminary measurement of the cosmic microwave background spectrum by the Cosmic Background Explorer (COBE) satellite. Astrophysical Journal, 1990, 354: L37.
4Smoot G F, Bennett C L, Kogut A, et al. Preliminary results from the COBE differential microwave radiometers: large angular scale isotropy of the cosmic microwave background. Astrophysical Journal, 1991,371: L1.
5Bennett C L, Kogut A, Hinshaw G, et al. Cosmic temperature fluctuations from two years of COBE differential microwave radiometers observations. Astrophysical Journol, 1994, 436: 423.
6Spergel D N, Bean R, Dore O, et al. Wilkinson Microwave Anisotropy Probe(WMAP)three year results: implications for cosmology, http://arxiv. org/abs/astro-ph/0603449, 2006.