Halvorson, George C., author
Jossey-Bass, 2003
Buku Teks
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
Artikel Jurnal
Artikel Jurnal