"United States Census, 1940," index and images, FamilySearch (https://familysearch.org/pal:/MM9.1.1/KQLZ-HNY : accessed 02 Oct 2014), Dora Oppewal in household of Peter Oppewal, Ward 3, Dunkirk, Dunkirk City, Chautauqua, New York, United States; citing enumeration district (ED) 7-29, sheet 7B, family 149, NARA digital publication of T627, roll 2509.