"Massachusetts, Town Clerk, Vital and Town Records, 1626-2001," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:QPZY-YQ55 : 31 October 2019), William Thayer and Sarah French, 23 Jun 1804; citing Marriage, Braintree, Norfolk, Massachusetts, United States, Massachusetts Secretary of the Commonwealth, Boston; FHL microfilm 007009769.
"Massachusetts Deaths, 1841-1915," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:N72R-XLM : 6 April 2020), William Thayer, 30 May 1849; citing Braintree, Massachusetts, v 41 p 7, State Archives, Boston; FHL microfilm 959,812.
Find a Grave, database and images (https://www.findagrave.com : accessed 19 July 2020), memorial page for William Thayer, Jr (26 Oct 1783–30 May 1849), Find A Grave: Memorial #19864214, citing Pond Street Cemetery, Braintree, Norfolk County, Massachusetts, USA ; Maintained by Marc Thayer, III (contributor 46542959) .