Towards evidence-based management of external resources: Developing design propositions and future research avenues through research synthesis

•We present a synthesis of 601 academic articles in the field of external resource management (ERM).•Our analysis reveals external resource management research to be concentrated on six interrelated themes.•We develop design propositions for supporting evidence-based management of external resources in firms.•We analyse the knowledge-trade between strategic management, marketing, and operations/supply chain management in the field of ERM.•We identify several opportunities for further research to advance evidence-based management in the field of ERM.