Mishura, Yu. S., and H. M. Shevchenko. 2004. “Euler Approximations of Solutions of Abstract Equations and Their Applications in the Theory of Semigroups”. Ukrains’kyi Matematychnyi Zhurnal 56 (3), 399-410. https://umj.imath.kiev.ua/index.php/umj/article/view/3762.