Gillespie, Sheena, author
Scott, Foresman and Company, 1986
Buku Teks
Cambridge University Press, 2007
eBooks
Spaventa, Lou J., author
McGraw-Hill, 2001
Buku Teks
Presley, John W., author
Holt, Rinehart and Winston, 1980
Buku Teks
McCrimmon, James W., author
Houghton Mifflin, 1984
Buku Teks