"United States Census, 1880," database with images, FamilySearch (https://www.familysearch.org/ark:/61903/1:1:MWXF-1QW : 28 November 2021), Bertha Bush in household of Peter H. Bush, Union Township, Centre, Pennsylvania, United States; citing enumeration district ED 220, sheet 132B, NARA microfilm publication T9 (Washington, D.C.: National Archives and Records Administration, n.d.), FHL microfilm 1,255,112.
"United States Census, 1910," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:MGQK-6MH : accessed 5 December 2021), Bertha E Davidson in household of Grant Davidson, Half Moon, Centre, Pennsylvania, United States; citing enumeration district (ED) ED 20, sheet 5A, family 84, NARA microfilm publication T624 (Washington D.C.: National Archives and Records Administration, 1982), roll 1325; FHL microfilm 1,375,338.