"Illinois, Cook County Marriages, 1871-1920," index, FamilySearch (https://familysearch.org/pal:/MM9.1.1/N7DF-XJY : accessed 11 May 2014), Nicolas Spoolstra and Grietje Friesema, 16 Aug 1889; citing Cook County, Illinois, , Cook County Courthouse, Chicago; FHL microfilm 1030184.