"Illinois, Cook County Marriages, 1871-1920," index, FamilySearch (https://familysearch.org/ark:/61903/1:1:N7C9-GVS : accessed 31 May 2015), Peter Sluiter and Sadie Schaaf, 20 Oct 1909; citing Chicago, Cook, Illinois, 520241, Cook County Courthouse, Chicago; FHL microfilm 1,030,467.