Wilson, Steve D., author
Burgess, 1967
Buku Teks
New York: McGraw-Hill Internanational Book Company, 1995,
Buku Referensi
[T.t]. [T.p.]. [T.th.]
Buku Referensi
Short, Ema, author
Cambridge University Press, 2013
Buku Teks
Jacson, Maria Elizabetha, author
Cambridge University Press, 2014
Buku Teks