McKillop, Alan Dugald, author
University of Kansas Press, 1956
Buku Teks
Hewit, Douglas, author
Longman , 1988
Buku Teks
Hewitt, Douglas, author
Longman, Green, 1992
Buku Teks
Gwynn, Stephen, author
Macmillan, 1950
Buku Teks
Morrison, Blake, author
Methuen , 1986
Buku Teks