Robinson, Alice M., author
Prentice-Hall, 1982
Buku Teks
Binns, Colin, author
University of Malaya Press, 2009
Buku Teks
Bowers, David, author
John Wiley & Sons, 2001
Buku Teks
Northouse, Laurel L., author
Appleton & Lange , 1998
Buku Teks
Ketchum, Paul A., author
John Wiley & Sons, 1984
Buku Teks