Lettres philosophiques /
Voltaire,1694-1778.
A Amsterdam, : Chez E. Lucas, au livre d'or.,
1734..
There are 3 eds. of the "Lettres philosophiques" with above place, date and pub., the original having 387 p. For full account see Bengesco. Voltaire; bibliographie, v. 2, p. 9-21.