1940 United States Census, database with images, FamilySearch (accessed 13 June 2016), Seth Karlzen, Ward 6, Rockford, Rockford Township, Winnebago, Illinois, United States; citing enumeration district (ED) 101-47, sheet 9A, family 218, NARA digital publication T627 (Washington, D.C.: National Archives and Records Administration, 2012), roll 913.
Death: 10 Oct 1986
Florida Death Index, 1877-1998, database, FamilySearch (accessed 13 June 2016), Keith S Karlzen, 10 Oct 1986; from "Florida Death Index, 1877-1998," index, Ancestry (www.ancestry.com : 2004); citing vol. , certificate number 94843, Florida Department of Health, Office of Vital Records, Jacksonville.
United States Social Security Death Index, database, FamilySearch (accessed 13 June 2016), Keith Karlzen, Oct 1986; citing U.S. Social Security Administration, Death Master File, database (Alexandria, Virginia: National Technical Information Service, ongoing).
United States World War II Army Enlistment Records, 1938-1946, database, FamilySearch (accessed 13 June 2016), Keith S Karlzen, enlisted 08 Nov 1945, Cp Grant, Illinois, United States; citing "Electronic Army Serial Number Merged File, ca. 1938-1946," database, The National Archives: Access to Archival Databases (AAD) (http://aad.archives.gov : National Archives and Records Administration, 2002); NARA NAID 126323, National Archives at College Park, Maryland.