7Chan, S. H. , Martin, J. , Kensinger, J. Corporate research and de- velopment expenditures and share value [ J ]. Journal of Financial E- conomics, 1990, 26:255-276.
8Comanor, W. S. and Seherer, F. M. Patent Statistics as a Measure of Technical Change [ J ]. Journal of Political Economy, 1969, 77 (3) : 392 - 398.
9Connolly, A. R. , Hirschey, M A value - based approach [ J ]. 1984, 66 (4) : 682 -686.
10R&D, market structure and profits: Review of Economics and Statistics, Griliches, Z. Issues in assessing the contribution of R&D to productivity growth [J]. Bell Journal of Economics, 1979, 10 (1) : 92 -116.
