edited by Sarah Gehlert; Teri Arthur Browne
John Wiley & Sons, 2012
Buku Teks
Keefe, Robert H.
Springer Publishing Company, 2013
Buku Teks
Northouse, Peter G.
Prentice-Hall, 1985
Buku Referensi
Christoper, Tom
Free Press, 1982
Buku Teks
Gahart, Betty L.
Mosby , 1995
Buku Referensi