edited by David C. Berliner and Robert C. Calfee
MacMillan Library Reference USA, 1996
Buku Referensi
edited by. David H. Jonassen
MacMillan Library Reference USA, 1996
Buku Referensi
Morphet, Edgar L. (Edgar Leroy), 1895-
Prentice-Hall, 1982
Buku Teks
Kubba, Sam
Elsevier, 2010
Buku Teks
Shepherd, Elizabeth J., 1960-
Facet Publishing, 2003
Buku Referensi