Cita APA (7a ed.)

Verschuur, G. L. (1997). Impact!: The threat of comets and asteroids. Oxford University Press.

Cita Chicago Style (17a ed.)

Verschuur, Gerrit L. Impact!: The Threat of Comets and Asteroids. Oxford, [England]: Oxford University Press, 1997.

Cita MLA (8a ed.)

Verschuur, Gerrit L. Impact!: The Threat of Comets and Asteroids. Oxford University Press, 1997.