Lynda, MEZGHICHERabah , KHEMIS2025-06-232025-06-232024http://dspace.univ-skikda.dz:4000/handle/123456789/4866In this work, three nonlinear functional di¤erential equations with delays and iterative terms are investigated. By virtue of a hybrid approach that combines the Banach, Schauder, and Krasnoselskii …xed point theorems with the Green’s functions method, we establish some su¢ cient conditions that guarantee the existence, uniqueness and stability of positive periodic solutions. The key idea consists to de…ne a Banach space and a subset of it in order to facilitate the study on the one hand, and on the other hand to ensure some desired requirements before converting the proposed problem into an equivalent integral equation whose kernel is a Green’s function. Then the application of certain …xed point theorems with the aid of some useful properties of the obtained Green’s kernel and some functional analysis tools help us to prove the sought results.endifferential equationsContinuous dependenceThesis