"Illinois, Northern District (Eastern Division), Naturalization Index, 1926-1979," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:2H5P-MSL : accessed 28 August 2015), Hilda Kats, 1954; citing Naturalization, Chicago, Cook, Illinois, United States, National Archives and Records Administration, Great Lakes Region, Chicago.