6Lev B,R&D and Capital Market ,Journal of Applied Corporate Finance, 1999.
7Hirsche & Weygandt (1985)Hirschey,M.and J.Weygandt. Amortization Policy for Advertising and Research and Development Expenditures:Journal of Accounting and Research,1985,23:326-335.
8Cohen. W and D.Levinthal,1989,Innovation and Learning:The Two faces of R&D.Economic Journal, vol 99,569-596.
9John Doukas, Lome Switzer. The Stock Market's Valuation of R&D Spending and Market Concentration.Journal of Economics & Business, May 1992,Vol.44 Issue 2,p95,20p,6charts.
10GRILICHES Z. Market value, R&D and patents [ J ]. Economic Letters, 1981, 7 (2) : 183 - 187.