edited by Peter Trudgill and J.K. Chambers
Longman, 1991
Buku Teks
Gray, Bennison
The Hague Mouton 1977
Buku Teks
Gray, Bennison
Mouton Publisher, 1977
Buku Teks
Poutsma, H.
P. Noordhoff, 1922
Buku Teks
Rosenthal, M. Sara, author
Lowell House, 2000
Buku Teks