Boyd, Denise
Pearson, 2005
Buku Teks SO
Craig, Garce J.
Prentice-Hall, 1992
Buku Teks SO
Zanden, James W. Vander
McGraw-Hill, 1993
Buku Teks SO
Turner, Jeffrey S.
Holt, Rinehart and Winston, 1987
Buku Teks SO
Turner, Jeffrey S.
Harcourt Brace College, 1995
Buku Teks SO