During the 2004-2012 window, research coalesced around designing closed-loop networks that integrate returns management, product remanufacturing, and disposal decisions. The literature framed Closed-Loop Supply Chain (CLSC) as a strategic asset, emphasizing profitability and value recovery through optimization of reverse channels, inventory policies, and process integration. Methodological approaches leaned on mathematical programming, simulation, and empirical validation, bridging operations research with supply-chain strategy. Historical Significance: This period established foundational optimization and design principles for closed-loop networks, catalyzing the incorporation of sustainability and resilience into mainstream supply-chain thinking, and setting the stage for subsequent work that treats returns management as essential to competitive advantage and drives the evolution from feasibility studies to profit-oriented, value-recovery-oriented network design.