APA (7e ed.) Bronvermelding

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

Chicago (17e ed.) Bronvermelding

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

MLA (9e ed.) Bronvermelding

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