Block, Stanley B.
Irwin, 1994
Buku Teks
by Arthur J. Keown, John D. Martin, J. William Petty, and David F. Scott
Prentice-Hall, 2005
Buku Teks
Asch, David
Crest Publishing House, 1999
Buku Referensi
Stephen A.Ross
Mc Graw Hill, 2009
Buku Teks
by Arthur J. Keown, John D. Martin, J. William Petty, David F. Scott
Prentice-Hall, 2001
Buku Teks