Carter, Ronald, author
Routledge, 2004
Buku Teks
Trudgill, Peter, author
Penguin, 1995
Buku Teks
Sari Kusuma Dewi, author
Fakultas Ilmu Pengetahuan dan Budaya Universitas Indonesia, 2016
UI - Skripsi Membership
Kern, Richard, author
Cambridge University Press, 2015
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Jahr, Ernst Hakon, author
Edinburgh University Press Ltd, 2014
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