Bodnar, George H.
Prentice-Hall, 1998
Buku Referensi
Bodnar, George H.
Prentice-Hall International, 1998
Buku Teks
Gelinas, Ulric J.
PWS-Kent, 1990
Buku Teks
Romney, Marshall B.
Pearson Education, 2015
Buku Teks SO
Hall, James A.
South-Western College , 2001
Buku Teks SO