"Edward Parker and Joseph Delaplaine to Thomas Jefferson, 27 April 1811," Founders Online, National Archives, https://founders.archives.gov/documents/Jefferson/03-03-02-0461. [Original source: The Papers of Thomas Jefferson, Retirement Series, vol. 3, 12 August 1810 to 17 June 1811, ed. J. Jefferson Looney. Princeton: Princeton University Press, 2006, p. 589.]

"Joseph Delaplaine to Thomas Jefferson, [ca. 24 April 1812]," Founders Online, National Archives, https://founders.archives.gov/documents/Jefferson/03-04-02-0545. [Original source: The Papers of Thomas Jefferson, Retirement Series, vol. 4, 18 June 1811 to 30 April 1812, ed. J. Jefferson Looney. Princeton: Princeton University Press, 2007, p. 663.]

"To James Madison from Joseph Delaplaine, 15 May 1812 (Abstract)," Founders Online, National Archives, https://founders.archives.gov/documents/Madison/03-04-02-0411. [Original source: The Papers of James Madison, Presidential Series, vol. 4, 5 November 1811–9 July 1812 and Supplement 5 March 1809 – 19 October 1811, ed. J. C. A. Stagg, Jeanne Kerr Cross, Jewel L. Spangler, Ellen J. Barber, Martha J. King, Anne Mandeville Colony, and Susan Holbrook Perdue. Charlottesville: University Press of Virginia, 1999, p. 385.]

"Thomas Jefferson to Joseph Delaplaine, 29 January 1821," Founders Online, National Archives, https://founders.archives.gov/documents/Jefferson/03-16-02-0480. [Original source: The Papers of Thomas Jefferson, Retirement Series, vol. 16, 1 June 1820 to 28 February 1821, ed. J. Jefferson Looney et al. Princeton: Princeton University Press, 2019, pp. 576–577.]

Joseph Delaplaine in Pennsylvania and New Jersey Church and Town Records, 1669–2013 (Ancestry.com)

United States Gazette (Philadelphia), 4 June 1824, page 3, column 2 (Newspapers.com).

Joseph Delaplaine at Find a Grave.

Joseph Delaplaine at FamilySearch.