Dolgin, Alexander
Springer, 2012
eBooks
Powell, G. Bingham
Pearson Education, 2015
Buku Teks SO
Owen, Robert
J.M. Dent & Sons , 1949
Buku Teks SO
Kamrava, Mehran
Routledge , 2000
Buku Teks SO
Lewis, David
Cambridge University Press, 2011
Buku Teks SO