On the theoretical front, resource based theory (Barney 1991; Grant 1991; Wernerfelt 1984) and its variants dynamic capability theory (Eisenhardtand Martin 2000; Teece, Pisano, and Shuen 1997), competency-based theory (Prahalad and Hamel 1990), knowledgebasedtheory (Grant 1996), organizational social capital theory (Leana and Van Buren 1999; Nahapiet and Ghoshal 1998), and intellectual capital theory (Edwinsson and Malone 1997; T. A. Stewart 1997) posit that firm-specific resources, assets, and capabilities that are valuable, rare, nonsubstitutable, or imperfectly imitable
can be an important source of sustainable competitive advantage and performance
differential among firms.