Bifurcation of periodic solutions of delay differential equation with two delays ✩

In this paper, we develop Kaplan–Yorke’s method and consider the existence of periodic solutions for delay differential equations with two delays. Especially, we study Hopf and saddle-node bifurcations of periodic solutions for the equation with parameters, and give conditions under which the bifurcations occur.  2003 Elsevier Inc. All rights reserved.