Dunleavy, Patrick
N.Y. Harvester , 1991
Buku Teks
Mueller, Dennis C.
Cambridge University Press, 2005
Buku Teks
Gwartney, James D.
The Reyden Press, 2000
Buku Teks
resources for the future, 1981
Buku Teks
Susan Dimock, Mohamad Al-Hakim, Garett MacSweeney; Alessandro Manduca-Barone, Anthony Anonacci
Nelson Education, 2013
Buku Teks