Three letters from Euler to Daniel Bernoulli, 1734-1740
According to Eneström (as of 1913), the originals may be found in the Herzoglichen Library in Gotha.
As the title suggests, this is a collection of three letters from Euler to Daniel Bernoulli. The letters in question are dated 16 February 1734, November 1734, and 15 September 1740.
Original Source Citation
Bibliotheca Mathematica, pp. 134-141, 145-153.