W. Foulsham, [date of publication not identified]
Buku Referensi
Kane, Charles W., author
Lincoln Town Press, 2009
Buku Teks
Silalahi, Marina, author
Universitas Indonesia, 2014
UI - Disertasi (Membership)
Barceloux, Donald G, author
John Wiley & Sons, 2008
Buku Teks
Galun, Esra, author
Imperial College Press, 1998
Buku Teks