McDowell, W. H.
Longman, 2002
Buku Teks
O`Neil, L. Peat
Writer's Digest Books, 1995
Buku Teks
Lester, James D. Sr., 1935-2006
Pearson, 2015
Buku Teks
Lester, James D. Sr., 1935-2006
Pearson, 2015
Buku Teks
Mahmoud, Shah
Betterway, 1992
Buku Referensi