APA-referens (7:e uppl.)

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

Chicago-referens (17:e uppl.)

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

MLA-referens (9:e uppl.)

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