Stewig, John Warren, author
Wadsworth, 1995
Buku Referensi
Kean, John M.
St. Martin's Press , 1976
Buku Teks
Centre for language in primary education, 1990
Buku Teks
Dougill, Peter
Open University Press, 1993
Buku Teks
Wray, David
Routledge, 1991
Buku Teks