Steinberg, David I., author
Nias Press, 2012
Buku Teks
Cambridge University Press, 2007
Buku Teks
Boulding, Kenneth E. (Kenneth Ewart), 1910-1993, author
Prentice-Hall, 1958
Buku Teks
edited by Robert M., asistance editor William A. Anderson
The George Washington niversity, 1982
Buku Teks
editor Robert M., asistance editor William A.Anderson
The George Washington University, 1982
Buku Teks