Bodnar, George H.
Prentice Hall International, 1995
Buku Teks
Gelinas, Ulric J.
PWS-Kent, 1990
Buku Teks
Gelinas, Ulric J.
South-Western , 2005
Buku Teks SO
Gelinas, Ulric J.
South-Western , 2005
Buku Teks SO
Moscove, Stephen A.
John Wiley & Sons, 1997
Buku Teks SO