edited by Don K. Price
Prentice-Hall, 1960
Buku Teks
Albright, Madeleine, author
Marimax Books, 2003
Buku Teks
edited by C.P. Ager
Bowker-Saur, 1992
Buku Referensi
Jong Un, Kim, author
Foreign Languages Pub. House, 2012
Buku Teks
The European Communities, 1997
Buku Teks