Cita APA (7a ed.)
Grego, P. (2008). Venus and Mercury, and how to observe them. Springer.
Cita Chicago Style (17a ed.)
Grego, Peter. Venus and Mercury, and How to Observe Them. New York: Springer, 2008.
Cita MLA (9a ed.)
Grego, Peter. Venus and Mercury, and How to Observe Them. Springer, 2008.
Precaución: Estas citas no son 100% exactas.