"United States Census, 1940," index and images, FamilySearch (https://familysearch.org/pal:/MM9.1.1/KMB3-ZDZ : accessed 22 Mar 2014), Dick Vanderwoude, Sanborn, Franklin Township, O'Brien, Iowa, United States; citing enumeration district (ED) 71-14, sheet 16B, family 333, NARA digital publication of T627, roll 1187.