"United States Census, 1940," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:KSV3-272 : 14 March 2018), Donald Welter in household of Leo M Welter, Ward 1, Little Falls, Little Falls City, Morrison, Minnesota, United States; citing enumeration district (ED) 49-22A, sheet 15A, line 34, family 335, 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 1939.
"Minnesota Death Index, 1908-2002," database, FamilySearch (https://familysearch.org/ark:/61903/1:1:V4H9-CRT : 4 December 2014), Donald Anthony Welter, 27 Sep 1996; from "Minnesota Death Index, 1908-2002," database, Ancestry (http://www.ancestry.com : 2001); citing Morrison, Minnesota, record 2583227, certificate number 028474, Minnesota Department of Health, Minneapolis.
"United States Social Security Death Index," database, FamilySearch (https://familysearch.org/ark:/61903/1:1:J1G4-GQM : 19 May 2014), Donald A Welter, 27 Sep 1996; citing U.S. Social Security Administration, Death Master File, database (Alexandria, Virginia: National Technical Information Service, ongoing).
Find A Grave, database and images (https://www.findagrave.com : accessed 28 June 2019), memorial page for Donald Anthony Welter (19 Aug 1927–27 Sep 1996), Find A Grave: Memorial #40142319, citing Minnesota State Veterans Cemetery, Little Falls, Morrison County, Minnesota, USA ; Maintained by Find A Grave (contributor 8) .