In this paper, an extension of Darbo?s fixed point theorem via the concept
of operators A(f;.) and ?-?-contractions in a Banach space has been
presented. We illustrate that some conditions of control functions ? and ?
can be omitted where they applied previously in [Mohammadi et al.,
Mathematics, 2020, 8(4), 492]. As an application, we study the existence of
solutions for a system of fractional integral equations. Finally, to support
the effectiveness of our results, we present an example.