H. Hogeveen
Wageningen Academic, 2011
eBooks
Northouse, Laurel L., author
Appleton & Lange , 1998
Buku Teks
Northouse, Peter G., author
Prentice-Hall, 1985
Buku Referensi
Berry, Dianne, author
Open University Press, 2007
Buku Teks
edited by Snehendu B. Kar, Rina Alcalay
Sage, 2000
Buku Teks