Although the literature presents many different ideas around the concept of the resource-advantage perspective, at its heart, the common theme is that the firm's resources are financial, legal, human, organisational, informational and relational; resources are heterogeneous and imperfectly mobile and that management's key task is to understand and organise resources for sustainable competitive advantage. Key theorists who have contributed to the development of a coherent body of literature include Jay B. Barney, George S. Day, Gary Hamel, Shelby D. Hunt, G. Hooley and C.K. Prahalad.