4Aboody, D. , and B. Lev, 2000, " Information asymmetry, R&D, and insider gains" Journal of Finance, 55, pp, 2747 - 2766.
5Amir, E , B. Lev and T. Sougiannis, 1999, "What value analysts?", SSRN Working Paper.
6Barth, M. , and R. Kasznik, 1999, "Share repurchase and intangible assets" , Journal of Accounting and Economics Journa, 28 ,pp. 211-241.
7Barth,M. ,R. Kasznik,and M. McNichols,2001 ,"Analyst coverage and intangible assets" , Journal of Accounting Reearch Journ,39, pp. I - 34.
8Bloom, N. , and J. V. Reenen, 2002, " Patents, real options and finn performance", The Economic Journal, 112, pp. 97-116.
9Chan,S. H. ,J. Martin,and J. Kensinger, 1990,"Corporate research and development expenditures and share value", Journal of Financial Economics, 26, pp. 255 - 276.
10Cockburn, l. , and Z. Guliches, 1988, " Industry effects and appropriability measure in the stock market's valuation of R&D and patents" ,American Economic. Review, 78, pp. 419 - 423.