1Thomas Jefferson to Nicolas G. Dufief, 27 October 1812 (Jefferson Papers)
Simpson, Thomas; Select Exercises for Young Proficients in the Mathematics [index entry]
2Thomas Jefferson to Louis H. Girardin, 7 July 1814 (Jefferson Papers)
Simpson, Thomas; Select Exercises for Young Proficients in the Mathematics [index entry]
3Thomas Jefferson to Louis H. Girardin, 12 May 1815 (Jefferson Papers)
Simpson, Thomas; Select Exercises for Young Proficients in the Mathematics [index entry]