“…Various definitions of barriers to entry have been proposed in the industrial organization literature, as the ones by Bain (1956), Stigler (1968), Ferguson (1974), Caves & Porter (1977), Fisher (1979), VonWeizsacker (1980), Demsetz (1982, Baumol & Willig (1981), Gilbert (1989), Geroski et al (1990), Carlton & Perloff (1994, Church & Ware (2000), McAfee et al (2004) and the OECD (2005).…”