Evans, B. Ifor
Penguin Books , 1948
Buku Teks
Collier, WIlliam Francis, author
Thomas Nelson and Son, 1920
Buku Teks
Wyld, H.C.
Oxford Blackwell 1953
Buku Teks
Hughes, Geoffrey, author
Blackwell , 2000
Buku Teks
Fennell, Barbara A., author
Blackwell Publishers, 2001
Buku Teks