Gobran, Alfonse, author
Prindle, Weber & Schmidt, 1975
Buku Teks
Kuebler, Roy R., author
John Wiley & Sons, 1976
Buku Teks
Wine, Lowell R.
Winthrop Publisher, 1976
Buku Teks
Horne, Elinor C., author
Yale University Press, 1961
Buku Teks
Lewis, Brenda Ralph, author
Random House, 1993
Buku Referensi