Christian Soe
McGraw-Hill, 2004
Buku Teks SO
Macridis, Roy C.
Dorsey Press, 1972
Buku Teks
editor, Amy Gutmann, Dennis Thompson
Thomson wadsworth, 2006
Buku Teks SO
Schlesinger, Rudolf B.
The Foundation Press, 1950
Buku Teks
Schlesinger, Rudolf B.
Foundation Press, 1950
Buku Klasik