Bladon, Rachel
Passport Books, [date of publication not identified]
Buku Teks
Routledge, 1998
Buku Teks
KITLV, 2002
Buku Referensi
Aritonang, Buha, compiler
Pusat Bahasa, Departemen Pendidikan Nasional, 2002
Buku Teks
edited by Peter Trudgill and J.K. Chambers
Longman, 1991
Buku Teks