“…We would like to mention that extensive investigations have been carried out on the bifurcation of delay differential equations, we refer the readers to [Faria & Magalhaes, 1995a, 1995bYu & Chen, 2004;Wang & Zou, 2005;Yuan & Wei, 2006;Wei & Fan, 2007;Chen & Wu, 2008;Taborda et al, 2009;Wijeratne et al, 2009;Yan & Li, 2009] and the references cited therein. Also there are a few papers on the bifurcation of neutral differential equations, see [Weedermann, 2006;Wang & Wei, 2008] and the references cited therein.…”