4Amihud, Yakov and Haim Mendelson, Asset Pricing and the Bid-ask Spread, Journal of Financial Economics, 1986, 17, pp.223- 249
5Boone, Jeff and Kris Raman, Off-balance-sheet R&D Assets and Market Liquidity, Journal of Accounting & Public Policy, 2001,20,pp.97 - 128.
6Lev, Baruch, Bhamt Sarath and Theodore Scugiannis, R&D Reporting Biases and Their Consequences, Working Paper, New York University, Stem School of Business, 2000.