edited by Maribel Gonzalez Pascual and Aida Torres Perez
Routledge, 2017
Buku Teks SO
by Michele Moore [and others]
The Falmer Press, 1996
Buku Teks
Gray, James, Sir, 1891-1975.
Cambridge University Press, 2013
Buku Teks
Pardede, Elda Luciana
Universitas Indonesia, 2001
UI - Skripsi Membership
Luther, William M.
American Management Association;, 2011
eBooks