APA (7th ed.) Citation

Harland, W. B. (1989). A geologic time scale 1989. Cambridge University Press.

Chicago Style (17th ed.) Citation

Harland, Walter Brian. A Geologic Time Scale 1989. New York: Cambridge University Press, 1989.

MLA (9th ed.) Citation

Harland, Walter Brian. A Geologic Time Scale 1989. Cambridge University Press, 1989.