6Bellalah M. Irreversibility, sunk costs and invest- ment under incomplete information [J]. R&D Management, 2001,31 (2) : 115 - 126.
7McDonald R, Siegel D. Option pricing when the underlying asset earns a below-equilibrium rate of return : a note[J]. Journal of Finance, 1984,39 (1) : 261-265.
8Carlssona C, Fullera R. A fuzzy approach to real option valuation[J]. Fuzzy Sets and Systems,2003, (139) : 297- 312.
9Carlssona C, et al. A fuzzy approach to R&D project portfolio selection[J]. International Journal of Approximate Reasoning, 2007, (44) : 93- 105.
10Merton R. Theroy of rational option pricing[J]. Bell Journal of Economics and Mangement Science, 1973, (4)141-183.