[1] M. Boudourides, D. Georgiou: 
Asymptotic behavior of nonlinear Stepanoff-bounded functional perturbation problems. Riv. Mat. Univ. Parma (4) 8 (1982). 
Zbl 0521.34051[2] D. Georgiou: Generalized asymptotic equivalence of functionally perturbed differential equations. Ph. D. dissertation, Democritus University of Thrace, Xanthi (Greece), 1981 (in Greek).