"United States Census, 1930," index and images, FamilySearch (https://familysearch.org/pal:/MM9.1.1/XMK9-ZFD : accessed 02 Jun 2014), Grace Groen in household of William Sterrenberg, Holland, Sioux, Iowa, United States; citing enumeration district (ED) 0014, sheet 7A, family 120, NARA microfilm publication T626, roll 683.