Cita APA (7th ed.)
Gingrich, N., & Maple, T. (2007). A contract with the Earth. Johns Hopkins University Press.
Cita Chicago (17th ed.)
Gingrich, Newt, i Terry Maple. A Contract with the Earth. Baltimore: Johns Hopkins University Press, 2007.
Cita MLA (9th ed.)
Gingrich, Newt, i Terry Maple. A Contract with the Earth. Johns Hopkins University Press, 2007.
Atenció: Aquestes cites poden no estar 100% correctes.