"Minnesota State Census, 1905," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:SP3N-Q4D : 18 February 2021), Nels Alfson, Clayton township, Mower, Minnesota; citing p. 11, line 3, State Library and Records Service, St.Paul; FHL microfilm 928,797.
"United States Census, 1910," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:M2L6-K7X : accessed 19 May 2022), Nels Alfson in household of Nels Alfson, Red Lake Falls, Red Lake, Minnesota, United States; citing enumeration district (ED) ED 239, sheet 9B, family 149, NARA microfilm publication T624 (Washington D.C.: National Archives and Records Administration, 1982), roll 690; FHL microfilm 1,374,703.