edited by Morton Borden
Rand McNally, 1961
Buku Teks
Franklin, Benjamin
The Spencer Press, 1936
Buku Teks
Blundell, Nigel
Octopus Books Limited, 1980
Buku Teks
McGraw-Hill, [date of publication not identified]
Buku Teks
Muller, Kal
Periplus , 1999
Buku Referensi