O`Neil, L. Peat
Writer's Digest Books, 1995
Buku Teks
Lester, James D. Sr., 1935-2006
Pearson, 2015
Buku Teks
Lester, James D. Sr., 1935-2006
Pearson, 2015
Buku Teks
Arthur, Diane
American Management Association, 1997
eBooks
Mahmoud, Shah
Betterway, 1992
Buku Referensi