Non-negative definite Lyapunov functionals are employed to obtain sufficient conditions that guarantee boundedness of solutions of system of functional differential equations with unbounded terms. The theory is illustrated with several examples regarding Volterra integro-differential equations.
"Exponential analysis of solutions of functional differential equations with unbounded terms." Banach J. Math. Anal. 3 (2) 28 - 41, 2009. https://doi.org/10.15352/bjma/1261086706