Aitchison, Jean, 1938-
Cambridge University Press, 1995
Buku Teks
Hazen, Kirk
Massachusetts : Wiley Blackwell, 2015
Buku Teks SO
Cambridge University Press, 2008
eBooks
Hughes, John P.
Random House, 1966
Buku Teks SO
Hughes, John P.
Random House, 1966
Buku Teks SO