6Caves R.E. Multinational Firms, Competition, and Productivity in Host-country Markets. Economica, New Series, 1974,Vol. 41, No.162.
7Djankov, Simeon and Hoekan, Bernard. Foreign Investment and Productivity Growth in Czech Enterprises. World Bank Economic Review, 2000, No. 14, pp. 49-64.
8Coe,D. and Helpman, E. International R&D Spillovers. European Economic Review, 1995, No. 39, pp. 859-887.
9Coe,D. Helpman, E. and Hoffmaister. North- South Spillover. Economic Journa, 1997, Vo.1 107(1), pp. 134-149.
10Lichtenberg and Pottelsberge. International R&D Spillovers: a Comment. European Economic Review, 1998, Vo. 42 (8),pp. 1843-1891.