Kieffer, George David, author
Serambi Ilmu Semesta, 2011
Buku Teks
Dignen, Bob, author
York Associates, 1999
Buku Teks
Booher, Diana
Prentice-Hall, 1991
Buku Teks
Rae, Leslie
McGraw-Hill, 1994
Buku Referensi
Mackenizie, John
Illinois: Dow Jones-Irwin, 1989
Buku Teks