Available Information:
https://music.metason.net/artistinfo?name=Sofia%20Steffan
https://www.nytimes.com/1957/02/17/archives/sophia-steffan-mezzosoprano-heard-in-recital-with-denver-oldham.html
https://www.nytimes.com/1959/12/09/archives/debut-recital-here-by-sophia-steffan.html
