Cambridge University Press, 2008
eBooks
Barr, Donald F.
Percetakan Universitas Cenderawasih, 1979
Buku Klasik
Aitchison, Jean, 1938-, author
Cambridge University Press, 1995
Buku Teks
Julian Bamfor edited by
:Cambridge University Press, 2004
Buku Teks
Voegelin, C.F.
Elsevier, 1977
Buku Teks