"United States Census, 1940," database with images, FamilySearch (https://www.familysearch.org/ark:/61903/1:1:KSK9-KH7 : 7 January 2021), Charles A Austad in household of Clarence M Austad, Chisago Lake Township, Chisago, Minnesota, United States; citing enumeration district (ED) 13-6, sheet 2A, line 30, family 36, Sixteenth Census of the United States, 1940, NARA digital publication T627. Records of the Bureau of the Census, 1790 - 2007, RG 29. Washington, D.C.: National Archives and Records Administration, 2012, roll 1913.