Gingrich, N., & Maple, T. (2007). A contract with the Earth. Johns Hopkins University Press.
芝加哥风格引文Gingrich, Newt, 与 Terry Maple. A Contract with the Earth. Baltimore: Johns Hopkins University Press, 2007.
MLA引文Gingrich, Newt, 与 Terry Maple. A Contract with the Earth. Johns Hopkins University Press, 2007.
警告：这些引文格式不一定是100％准确.