Artikel Jurnal
UNESCO, 1966
Buku Teks
Olive III, J Fred
Educational Technology Publications, 1995
Buku Referensi
editor-in-chief, Harold E. Mitzel
Free Press, 1993
Buku Referensi
editor-in-chief, Marvin C. Alkin
MacMillan Library Reference USA, 1992
Buku Referensi