Perrin, Porter G., author
Glenview, 1968
Buku Teks
Wilson, Kevin, 1958- , author
[American Management Association;, ], 2011
eBooks
Merja Kytö and Päivi Pahta edited by
Cambridge University Press, 2016
Buku Teks
Lennard, John, author
University Press, 2005
Buku Referensi
Harris, Muriel, author
Prentice-Hall, 1997
Buku Referensi