Christ, Henry
Lexington, 1982
Buku Teks
Gramley, Stephan, author
Routledge, 2004
Buku Teks SO
Frank, Marcella, author
Prentice-Hall, 1972
Buku Teks SO
New, W.H., author
Copp Clark Pitman, 1986
Buku Teks
Crowell, Thomas Lee, author
McGraw-Hill, 1987
Buku Referensi