[2] ˇCERM´AK, J.: A change of variables in the asymptotic theory of differential equations with unbounded delays, J. Comput. Appl. Math. 143 (2002), 81-93.10.1016/S0377-0427(01)00500-3
[13] MAKAY, G.-TERJ´EKI, J.: On the asymptotic behaviour of the pantograph equations, Electron. J. Qual. Theory Differ. Equ. 2 (1998), 1-12.10.14232/ejqtde.1998.1.2