1. T. Kato and J. B. McLeod, “The functional-differential equation y ‵ (x) = ay(λx) + by(x),” Bull. Amer. Math. Soc., 77, 891–937 (1971).
2. T. Kato, “Asymptotic behaviour of solutions of the functional-differential equation y ‵ (x) = ay(λx) + by(x),” in: K. Schmitt (editor), Proc. of the Conf. “Delay and Functional Differential Equations and Their Applications,” Academic Press, New York (1972).
3. N. G. de Bruijn, “The difference-differential equation F ‵ (x) = eαx + βF(x − 1). I, II,” Indag. Math., 15, 449–464 (1953).
4. P. O. Frederickson, “Series solutions for certain functional-differential equations,” in: Lecture Notes in Mathematics, 243 (1971), pp. 249–254.
5. J. Carr and J. Dyson, “The functional differential equation y ‵ (x) = ay(λx) + by(x),” Proc. Roy. Soc. Edinburgh. Sect. A, 74, 165–174 (1976).