1. Bellman, R., Cooke, K.L.: Differential-Difference Equations. Academic Press, New York (1963)
2. Burton, T.A., Frumochi, T.: Fixed points and problems in stability theory for ordinary and functional differential equations. Dyn. Syst. Appl. 10, 89–116 (2001)
3. Burton, T.A.: Stability by Fixed Point Theory for Functional Differential Equations. Dover Publications, New York (2006)
4. Burton, T.A., Frumochi, T.: Asymptotic behavior of solutions of functional differential equations by fixed point theorems. Dyn. Syst. Appl. 11, 499–519 (2002)
5. Ardjouni, A., Djoudi, A.: Fixed points and stability in linear neutral differential equations with variable delays. Nonlinear Anal. 74, 2062–2070 (2011)