found: Wagner, R. Opera arias, 1958
found: New Grove dict. of opera (Nilsson (Svennsson), (Märta) Birgit; b. May 17, 1918, Västra Karups; Swedish soprano)
found: Kutsch/Riemens. Grosses Sängerlexikon, 1987 (Nilsson, Birgit; b. May 17, 1918, Karup, Sweden; soprano; married to veterinarian Bertil Niklasson)
found: Int. ww in mus., 14th ed. (Nilsson, Birgit (Fru Bertil Niklasson); b. May 17, 1918, Karup, Sweden; soprano)
found: Baker, 8th ed. (Nilsson, (Märta) Birgit; b. May 17, 1918, Västra Karups; Swedish soprano)
found: AP news via Yahoo! www home page, Jan. 11, 2006 (Birgit Nilsson; funeral held Jan. 11, 2006, but officiating clergy did not know date of death)
found: Svenska dagbladet www home page, Jan. 11, 2006 (Birgit Nilsson; d. Dec. 25, 2005)
found: Info. converted from 678, 2012-10-02 (b. 1918)
Nilsson, Birgit
