Analyticity of solutions of nonlinear evolution equations

Analyticity in t of solutions u(t) of nonlinear evolution equations of the form $\text{u′ + A(t, u)u = ?(t, u), t > 0, u(0) = u}{}_0$, is established under suitable conditions on $\text{A(t, u), ?(t, u),}\text{and}\text{u}{}_0$. An application is given to quasilinear parabolic equations.