Scott, Geoffrey
W.W. Norton, 1999
Buku Teks SO
Hart, James D.
Oxford University Press, 1950
Buku Teks SO
Lieberson, Stanley
Yale University Press, 2000
Buku Teks
James, P.D.
Sphere, 1987
Buku Teks SO
Roberts, Sam.
BBC Worldwide Limited, 2004
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