Verschuur, G. L. (1996). Impact!: The threat of comets and asteroids. Oxford University Press.
Lua i Stíl Chicago (17ú heag.)Verschuur, Gerrit L. Impact!: The Threat of Comets and Asteroids. New York: Oxford University Press, 1996.
Lua MLA (9ú heag.)Verschuur, Gerrit L. Impact!: The Threat of Comets and Asteroids. Oxford University Press, 1996.
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