Best, Robert
Longman Group Limited, 1986
Buku Teks SO
Fisher, David
Lonngman , 1970
Buku Teks SO
Foers, E.
Oxford University Press, 1957
Buku Teks SO
Allsop, Jake
Cassell, 1981
Buku Teks SO
Ashabranner, Brent K.
Hougton Mifflin Company, 1961
Buku Teks SO