"United States Census, 1940," index and images, FamilySearch (https://familysearch.org/pal:/MM9.1.1/KQLZ-SPJ : accessed 02 Oct 2014), Jennie Oppewal in household of Gerret Wykster, Ward 3, Dunkirk, Dunkirk City, Chautauqua, New York, United States; citing enumeration district (ED) 7-29, sheet 15B, family 360, NARA digital publication of T627, roll 2509.