Green, Constance McLaughlin, 1897-1975
Harper & Row, Publishers, 1965
Buku Teks
Schnore, Leo F.
The Free Press, 1965
Buku Teks
Northam, Ray M., author
John Wiley & Sons, 1979
Buku Teks
Hallenbeck, Wilbur C., author
Harper & Brothers , 1951
Buku Teks
edited by Joseph E. Haring
Houghton Miffiln, 1972
Buku Teks