edited by Russell C. Koza, Leonard L. Hurst and Gerald A. Giebink
Colorado Associated University Press, 1974
Buku Teks
Halvorson, George C., author
Jossey-Bass, 2003
Buku Teks
Weingand, Darlene E., author
Libraries Unlimited, 1999
Buku Teks
O`Brein, James M., author
[publisher not identified], [date of publication not identified]
Artikel Jurnal
Artikel Jurnal