Elleh, Nnamdi
McGraw-Hill, 1997
Buku Teks SO
Dodge, Dorothy
D. Van Nostrand, 1966
Buku Teks SO
Kegley, Charles William, Jr.
Wadsworth, 2009
Buku Teks SO
Kegley, Charles William, Jr.
St. Martin`s Press, 1997
Buku Teks SO
Kegley, Charles William, Jr.
Wadsworth and Cengage Learning, 2013
Buku Teks SO