Porter, Charles O. (Charles Orlando), 1919-2006, author
Macmillan, 1961
Buku Teks
Cambridge University Press, 1997
eBooks
Rogers, William D., author
Random House, 1967
Buku Teks
Greenberg, Edward S., author
Pearson/Longman, 2005
Buku Teks
edited by Eduardo P. Archetti
MacMillan Education, 1987
Buku Teks