Bowden, Edwin T., author
Holt, Rinehart and Winston, 1963
Buku Teks
Doggett, Sister Aileen
The Ambassador Publication, 1990
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Springer, 2012
eBooks
Eye, Alexander von, author
Lawrence erlbaum assossiate, 2005
Buku Teks
The Indonesian general election Commission, 2001
Buku Teks