NASA
Nasa: Sputnik and the Dawn of the Space Age
This site from NASA describes the impact that Sputnik had in triggering the space race.
NASA
Nasa: Sputnik and the Origins of the Space Age
NASA provides a paper providing a background to the Sputnik launch and the U.S. response.
NASA
Nasa: Sputniks 1, 2, and 3
NASA provides a paper that "deals with the politics, planning and technology of the period 1946-1958" in the Sputnik program.
NASA
Nasa: "Pravda" Press Release
NASA provides the full text from the tersely worded "Pravda," the Russian national newspaper, that announced the successful launch of Sputnik.