Leritz, Len, author
[American Management Association;, ], 1994
eBooks
Weeks, Edward, author
Writer`s Digest Books, 1962
Buku Teks
Palmer, Barbara, author
Routledge, 2008
Buku Teks
Johnston, Jerome
Sage, 1982
Buku Teks
Gilbert, Doris W.
Prentice-Hall, 1991
Buku Teks