"Iowa, County Marriages, 1838-1934," index, FamilySearch (https://familysearch.org/pal:/MM9.1.1/XJCL-RSN : accessed 26 Apr 2014), Jacobus Steinberg and Katharina Snoek, 02 Dec 1897; citing Rock Valley, Sioux, Iowa, United States; FHL microfilm 1404834.