“…Although the method in Ngoc (2013) does include criteria to determine the stability of non-positive linear systems, the structure of the delay function r(•) ∈ [0, r 2 ] R therein is still restrictive. On the other hand, the synthesis (stability analysis) methods proposed in Münz et al (2009); Goebel et al (2011); Gouaisbaut et al (2015); Seuret et al (2015); Feng & Nguang (2016), which are developed to handle linear distributed delay systems with constant delay values, may not be easily extended to cope with systems with an unknown time-varying delay r(•) ∈ [r 1 , r 2 ] R . This is especially true for the approximation approaches established in Münz et al (2009); Goebel et al (2011); Gouaisbaut et al (2015); Seuret et al (2015), since the approximation coefficients can become nonlinear with respect to r(t) if the distributed delay kernels are approximated over [−r(t), 0].…”