In 1739 and 1740 he published further work on the integral calculus, proving the existence of integrating factors for solving first order differential equations (a topic which also interested Johann Bernoulli, Reyneau and Euler).
Sa 1739 at 1740 siya nai-publish ng karagdagang trabaho sa integral calculus, proving ang pagkakaroon ng pagsasama ng mga kadahilanan para sa solving unang order kaugalian equation (isang paksa na interesado din Johann Bernoulli, Reyneau at Euler).