Issel, L. Michele
Jones & Bartlett Learning, 2014
Buku Teks
Issel, L. Michele
Jones and Barlett Publ., 2004
Buku Teks
by W. R. Ferguson
Applied Science Publisher, 1973
Buku Teks SO
Leedy, Paul D.
Pearson Education, 2005
Buku Teks SO
Surmanek, Jim
NTC Business Books, 1989
Buku Teks SO