Padelford, Norman J., author
Macmillan, 1962
Buku Teks
Nikolaos Tzifakis, editor
[Springer, ], 2012
eBooks
Lerche, Charles O., Jr., author
Oxford University Press, 1956
Buku Teks
Bozeman, Adda B., author
Princeton University Press, 1960
Buku Teks
edited by Arend Lijphart
Allyn and Bacon, 1966
Buku Teks