Keel, Pamela K., author
Pearson/Prentice Hall, 2005
Buku Teks
edited by Craig Donnellan
Independence Educational Publishers, 1994
Buku Teks
Keel, Pamela K., author
Pearson Prentice-Hall, 2005
Buku Teks
Unesco, 1981
Buku Teks
Beevers, D. Gareth, author
Wiley Blackweel, 2015
Buku Teks