Novas, Himilce , author
A Plume Book, 2004
Buku Teks
Young, Bruce K., author
Bantam Dell, 2008
Buku Teks
McKnight-Trontz, Jennifer, author
Torrent Books, 2004
Buku Teks
Bagnall, Philip M., author
Springer, 2012
eBooks
National Geographic Society, 2007
Buku Referensi