"United States Census, 1920," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:MWTR-RPQ : accessed 24 September 2018), Herbert Gay in household of Sam Gay, Bemidji Ward 3, Beltrami, Minnesota, United States; citing ED 25, sheet 15A, line 1, family 269, NARA microfilm publication T625 (Washington D.C.: National Archives and Records Administration, 1992), roll 822; FHL microfilm 1,820,822.
"United States Census, 1930," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:X3CP-54G : accessed 24 September 2018), Herbert L Gay in household of Samuel Gay, Durand, Beltrami, Minnesota, United States; citing enumeration district (ED) ED 17, sheet 1A, line 35, family 9, NARA microfilm publication T626 (Washington D.C.: National Archives and Records Administration, 2002), roll 1079; FHL microfilm 2,340,814.
"United States Census, 1940," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:KSLQ-493 : 14 March 2018), Herbert L Gay in household of Sam M Gay, Burnhamville Township, Todd, Minnesota, United States; citing enumeration district (ED) 77-8, sheet 7A, line 40, family 121, 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 1964.