Charles T. Downey, Renata Tebaldi Soars above Her Last Finale (December 20, 2004)
Charles T. Downey, Victoria de Los Angeles Dead at 81 (January 29, 2005)
Jens F. Laurson, Birgit Nilsson on Disc (January 15, 2006)
I never had the chance to hear her sing live, but her sound on recordings is nothing short of wondrous, Isolde or Brünnhilde piercing through with clarion beauty no matter how powerful the orchestra. For some great pictures, see the slide show from the New York Times, where there are also some great audio clips. What a voice!