Metcalf, Richard W., author
Harcourt Brace Jovanovich, 1990
Buku Teks
Lamb, Charles W., author
Houghton Mifflin, 1987
Buku Teks
Clark, Mary Jo, author
Appleton & Lange, 1999
Buku Teks
Folks, J. Leroy, author
John Wiley & Sons, 1981
Buku Teks
Lamont, Douglas, author
Blackwell Publishers, 1996
Buku Referensi