Bodsworth, C., author
The English Languange Book Society, 1963
Buku Teks
Bodsworth, C.
Longmans Green and Co LTD, 1963
Buku Teks
Hosford, William F., author
Cambridge University Press , 2012
Buku Teks
Engel, Thomas, author
Pearson Prentice Hall, 2006
Buku Teks
Alberty, Robert A., author
John Wiley & Sons, 1992
Buku Teks