Çetin E.Topal F.S.2019-10-272019-10-2720121085-33751085-3375https://doi.org/10.1155/2012/707319https://hdl.handle.net/11454/26623Let be a periodic time scale in shifts ? ±. We use a fixed point theorem due to Krasnosel'ski to show that nonlinear delay in dynamic equations of the form x ?(t) = - a(t)x ?(t) + b(t)x ?(? -(k,t)) ? - ?(k,t) + q(t,x(t), x(? -(k, t))), t ? has a periodic solution in shifts ? ±. We extend and unify periodic differential, difference, h -difference, and q -difference equations and more by a new periodicity concept on time scales. © 2012 Erbil Çetin and F. Serap Topal.en10.1155/2012/707319info:eu-repo/semantics/openAccessArticle2012Q4