"United States Census, 1930," index and images, FamilySearch (https://familysearch.org/ark:/61903/1:1:XMV9-KMK : accessed 5 April 2015), Jennie Van Der Hart in household of William Van Der Hart, Black Oak, Mahaska, Iowa, United States; citing enumeration district (ED) 0003, sheet 6B, family 135, line 92, NARA microfilm publication T626 (Washington D.C.: National Archives and Records Administration, 2002), roll 667; FHL microfilm 2,340,402.