Groban, Josh
Reprise Records, 2007
Multimedia
Pruett, Jon, author
Chicago Review Press, 2004
Buku Teks
Willis, Barry R
Pine Valley Music, 1989
Buku Teks
Napitupulu, Elviera, author
1989
UI - Skripsi (Membership)
Boyden, David D., author
Alfred A. Knopf , 1956
Buku Teks