1Ferdinand R. Hassler to Thomas Jefferson, 5 January 1820 (Jefferson Papers)
Hassler, Ferdinand Rudolph; letters from [index entry]
2Ferdinand R. Hassler to Thomas Jefferson, 10 December 1819 (Jefferson Papers)
Hassler, Ferdinand Rudolph; letters from [index entry]
3Enclosure: Ferdinand R. Hassler to Robert Patterson, 2 December 1816 (Jefferson Papers)
Hassler, Ferdinand Rudolph; letter from, to R. Patterson [index entry]
4Ferdinand R. Hassler to Thomas Jefferson, 1 August 1813 (Jefferson Papers)
Hassler, Ferdinand Rudolph; letters from [index entry]