... mobility of human resources, the system of innovation and national productivity. Despite the importance of the full spectrum of skills, the literature on mobility of human resources and their ... Lopez and Schiff (1995, 1998) and Ottaviano and Thisse (2002).20 See Lee (1966), Da Vanzo (1981) and Carrington et al. (1996).21 We must assume homogenous labour (supply) and production (demand).22 ... (1987), Knapp and Graves (1989), Courant and Deardorff (1993), Haas and Serow (1993), Clark and Knapp (1995), Mueser and Graves (1995), Goetz et al. (1996), Brueckner et al. (1999) and Deller et...