edited by Sarah Gehlert; Teri Arthur Browne
John Wiley & Sons, 2012
Buku Teks
Keefe, Robert H.
Springer Publishing Company, 2013
Buku Teks
Christoper, Tom
Free Press, 1982
Buku Teks
Northouse, Peter G.
Prentice-Hall, 1985
Buku Referensi
[edited by] Ron Kraus, George Stricker, Cedric Speyer
Elsevier , 2010
Buku Teks