Find A Grave, database and images (https://www.findagrave.com : accessed 01 February 2018), memorial page for Wilhelm Henie (7 Sep 1872–10 May 1937), Find A Grave: Memorial #21026711, citing Oslo Western Civil Cemetery, Oslo, Oslo kommune, Oslo fylke, Norway ; Maintained by NatalieMaynor (contributor 46770385) . (Husband's memorial page, which contains an image of their headstone with her date information)
"United States Census, 1940," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:K97C-YQB : accessed 1 February 2018), Sonja Heina in household of Selma Heina, Tract 387, West Hollywood, Beverly Hills Judicial Township, Los Angeles, California, United States; citing enumeration district (ED) 19-63, sheet 12B, line 55, family 387, Sixteenth Census of the United States, 1940, NARA digital publication T627. Records of the Bureau of the Census, 1790 - 2007, RG 29. Washington, D.C.: National Archives and Records Administration, 2012, roll 222.