Letter from Benjamin Franklin to Josiah and Abiah Franklin, 6 September 1744.Benjamin Franklin Papers.Philadelphia: American Philosophical Society
2.
Letter from Benjamin Franklin to Sir John Pringle, December 21, 1757. In: FranklinBenjamin. Experiments and Observations on Electricity made at Philadelphia in America, 4th edn.London: David Henry, 1769
3.
Letter from Sir John Pringle to Benjamin Franklin, March 1767.Benjamin Franklin Papers.Philadelphia: American Philosophical Society
4.
Letter from Benjamin Franklin to Cadwalader Evans, 20 February 1768. In: HazardSamuel, ed. Hazard's Reg Pennsylvania1835; 1666
5.
The Pennsylvania Gazette 30 December 1736
6.
Letter from Benjamin Franklin to William Vassall, 29 May 1746; Letter from Benjamin Franklin to John Perkins, 13 August 1752.Benjamin Franklin Papers.Philadelphia: American Philosophical Society
7.
Letter from Benjamin Franklin to John Franklin, 8 December 1752.History of Medicine Collections.New York: Academy of Medicine
8.
LetochaCharles E.The Invention and Early Manufacture of Bifocals.Survey of Ophthalmology1990; 35: 226–35
9.
Letter from Benjamin Franklin to George Whatley, 21 August 1784
10.
Letter from Benjamin Franklin to Jan Ingenhousz, 28 August 1785
11.
Letter from Benjamin Franklin to Mary Stevenson Hewson, 7 September 1783. Benjamin Franklin Papers.Conneticut: Yale University Library
12.
Letter from Benjamin Franklin to the Comte de Buffon, 4 November 1787
