8Greenwald, Bruce and Joseph E. Stiglitz. Externalities in Economies with Imperfect Information and Incomplete Markets. Quarterly Journal of Economics, 1986, 101 : 229 -264.
9Mansfield, E. Schwartz, M. and Wagner, S. Imitation Costs and Patents: An Empirical Study. Economic Journal, 1981, 91: 907-918.
10Mansfield, E. Patents and Innovation: An Empirical Study. Management Science, 1986, 32, 173-181.