Cita APA (7a ed.)

Harland, W. B. (1990). A Geologic time scale 1989. University Press.

Cita Chicago Style (17a ed.)

Harland, Walter Brian. A Geologic Time Scale 1989. Cambridge: University Press, 1990.

Cita MLA (8a ed.)

Harland, Walter Brian. A Geologic Time Scale 1989. University Press, 1990.