Forde, Helen, author
Facet Publishing, 2007
Buku Teks
Vowels : J.P. Kelly and J.B. Heley
Majalah, Jurnal, Buletin
Forde, Helen, author
Facet Publishing, 2007
Buku Teks
Wilfred D. Webb
Thomas Y. Crowell Company, 1961
Buku Teks
Phoenix Publishing Limited, 2011
Buku Referensi