Northouse, Peter G., author
Prentice-Hall, 1985
Buku Referensi
Christoper, Tom, author
Free Press, 1982
Buku Teks
Gahart, Betty L., author
Mosby , 1995
Buku Referensi
Smith, Michael J., author
Oxford University Press, 2010
Buku Teks
[edited by] Ron Kraus, George Stricker, Cedric Speyer
Elsevier , 2010
Buku Teks