"United States World War I Draft Registration Cards, 1917-1918", database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:74ZV-V62M : 23 February 2021), Orvil Curtis Allen, 1917-1918.
"United States Census, 1900," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:MS4M-2Q6 : accessed 21 November 2021), Orvel C Allen in household of Thomas J Allen, Allison Township, Lawrence, Illinois, United States; citing enumeration district (ED) 107, sheet 7B, family 135, NARA microfilm publication T623 (Washington, D.C.: National Archives and Records Administration, 1972.); FHL microfilm 1,240,317.
"Indiana Marriages, 1811-2019," database with images, FamilySearch (https://www.familysearch.org/ark:/61903/1:1:KZCC-88L : 18 October 2021), Orville C Allen and Lula May Vernon, 16 Dec 1911; citing Orange, Indiana, United States, Marriage License, Indiana Commission on Public Records, Indianapolis; FHL microfilm 005014451.