Sage, 1987
Buku Teks SO
edited by Sergio Diaz-Brizuets and Sidney Weintraub
Westview Press , 1991
Buku Teks SO
Wiarda, Howard J.
Westview Press, 1992
Buku Teks SO
Hanke, Lewis
D. Van Nostrand, 1959
Buku Teks SO
Keegan, William F.
Oxford University Press, 2017
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