Cottrell, Randall R., author
Pearson, 2014
Buku Teks
Williams, Caroline, author
Chandos, 2006
Buku Teks
Galli, Nicholas
John Wiley & Sons, 1978
Buku Teks
Healey, Bernard J., author
Jossey- Bass, 2012
Buku Teks
Goldsmith, Seth B., author
Jones & Bartlett, 2011
Buku Teks