Hardie, Alec M.
Longman , 1971
Buku Teks
Blunden, Edmund
Macmillan's Pocket Lib., 1951
Buku Teks
Bernard, John D., author
Cambridge University Press, 1989
Buku Teks
Farber, Marvin., 1901-1980
Harvard University Press, 1943
Buku Teks
Bullard, Paddy, author
Cambridge University Press, 2011
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