VasylykV. B., and MakarovV. L. “Exponentially Convergent Method for the First-Order Differential Equation in a Banach Space With Integral Nonlocal Condition”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 66, no. 8, Aug. 2014, pp. 1029–1040, https://umj.imath.kiev.ua/index.php/umj/article/view/2197.