"Iowa, Marriages, 1809-1992," index, FamilySearch (https://familysearch.org/pal:/MM9.1.1/XV9V-217 : accessed 20 Jun 2014), Martin Olson and Belle Eglund, 16 Mar 1894; citing Hamilton,Iowa, reference ; FHL microfilm 1404699.
"Iowa State Census, 1925," database with images, FamilySearch (https://www.familysearch.org/ark:/61903/1:1:QKQH-LLZW : 21 June 2020), Nels Olson, Blairsburg, Hamilton, Iowa, United States; citing Blairsburg, Hamilton, Iowa, United States, Iowa State Historical Department, Des Moines; FHL microfilm .