Llibre, Jaume et Tar.a, Alexandrina-alina, Periodic orbits for some systems of delay differential equations, Acta mathematica Sinica. English series (Print) , 24(2), 2008, pp. 267-274
We provide sufficient conditions for the existence of periodic orbits of some systems of delay differential equations with a unique delay. We extend Kaplan-Yorke.s method for finding periodic orbits from a delay differential equation with several delays to a system of delay differential equations with a unique delay.