1Horatio G. Spafford to Thomas Jefferson, 3 April 1809 (Jefferson Papers)
patents; of H. G. Spafford [index entry]
2Horatio G. Spafford to Thomas Jefferson, 30 March 1814, with Postscript 7 April 1814 (Jefferson Papers)
patents; of H. G. Spafford [index entry]
3Horatio G. Spafford to Thomas Jefferson, 23 January 1815 (Jefferson Papers)
patents; of H. G. Spafford [index entry]
4Horatio G. Spafford to Thomas Jefferson, 15 February 1815 (Jefferson Papers)
patents; of H. G. Spafford [index entry]
5Horatio G. Spafford to Thomas Jefferson, 18 February 1815 (Jefferson Papers)
patents; of H. G. Spafford [index entry]
6Thomas Jefferson to Horatio G. Spafford, 15 March 1815 (Jefferson Papers)
patents; of H. G. Spafford [index entry]
7Horatio G. Spafford to Thomas Jefferson, 9 January 1816 (Jefferson Papers)
patents; of H. G. Spafford [index entry]