Hello, I was wondering where I can find a proof to the following theorem: If F is differentiable at every pt. of [a,b] and if F' is lebesque on [a,b] then F(x) = int(f,dt,a,x) a<=x<=b. And the converse. He gives the theorem are page 324 and a reference in his bibliography. I was wondering where I detailed proof for this theorem.