Sharp, Frank Chapman
Appleton-Century-Croft , 1937
Buku Teks
Jennings, Marianne Moody, author
South-Western, 2009
Buku Teks
Hodges, Luther H., author
Prentice-Hall, 1963
Buku Teks
Velasquez, Manuel G., author
Pearson, 2006
Buku Teks
Stanwick, Peter A., author
Pearson, 2009
Buku Teks