West, Anthony R.
John Wiley & Sons, 2014
Buku Teks SO
Elliott, Roger J.
English Language Book Society, 1978
Buku Teks SO
Thomason, Michael
Reston Publishing, 1979
Buku Referensi
Academic Press, 1984
Buku Teks SO
Goto, Kazuhiro Sylvester
Elsevier, 1988
Buku Teks SO