London : Hamish Hamilton Ltd
Majalah, Jurnal, Buletin
Artikel Jurnal
edited by Kieran Walshe and Judith Smith
Open University Press, 2006
Buku Teks
edited by Kieran Walshe and Judith Smith
McGraw-hill Open Univer, 2011
Buku Teks
Cama, Rosalyn
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Buku Teks