Klippel, F. (2007). Keep talking. Cambridge University Press.
Cita Chicago (17th ed.)Klippel, Friederike. Keep Talking. Cambridge: Cambridge University Press, 2007.
Cita MLA (9th ed.)Klippel, Friederike. Keep Talking. Cambridge University Press, 2007.
Atenció: Aquestes cites poden no estar 100% correctes.