“…For example, some sufficient conditions ensuring the global exponential stability of positive periodic solutions and almost periodic solutions of classical Nicholson's blowflies equation with time-varying delays have been established in [10] and [11,12] respectively. Furthermore, the global exponential stability of positive almost periodic solutions for Nicholson's blowflies models involving nonlinear density-dependent mortality terms has been obtained in [14,15,16,17,18,19,20]. The results included in each paper of [10,11,12,14,15,16,17,18,19,20] gave an answer to the open problem: 3338 CHUANGXIA HUANG, HUA ZHANG AND LIHONG HUANG Find global stability conditions for the positive periodic solution of delayed non-autonomous Nicholson's blowflies equation, which was proposed by Berezansky et al [21].…”