Hubbard, L. Ron, 1911-1986, author
Bridge Publications, Inc., 2012
Buku Referensi
Jenks, C. Wilfred
Oceana, 1963
Buku Teks
Corbett, Michael,
Longman, 1982.
Buku Teks
Miles, Malcolm
[publisher not identified], 2000
Buku Teks
Faludi, Andreas
Pergamon Press, 1978
Buku Teks