Thomas, Kenneth S., author
Springer, 2012
eBooks
Paust, Jordan J., author
St. Paul Minn, 2000
Buku Teks
Wallace-Murphy, Tim, author
Watkins, 2006
Buku Teks
Trofimenko, Genrikh
Progress Publishers, 1986
Buku Teks
Bureau of International Information Programs United States Department of State, 2004
Buku Teks