Ennen, Edith
North-Holland Publishing, 1979
Buku Teks
Coldstream, Nicola
Oxford University Press, 2002
Buku Teks
Nicholas, David, author
Longman, 1992
Buku Teks
McGarry, Daniel D., author
Littlefield, Adams, 1968
Buku Teks
Murray, Alexander, author
Oxford University Press, 2016
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