3Voorhees E M, Harmann D K. Overview of the 6th text retrieval conference. In Proc. of the 6th Text Retrieval Conferenee(TREC- 3)[C]. Gaithersburg, USA, 1991.
4Raghavan V V, Jung G S, Balhnann P. A critical investigation of recall and precision as measures of retrieval system performance. ACM Transactions on Office and Information System [J]. 1989, 7(3).
5Shaw Jr W M, Burgin R, Howell P. Performance standards and evaluation in IR test collection: Cluster-based retriveval models.Infbrmation Processing and Management [J]. 1997, 33(1).
6Shaw Jr W M, Burgin R, Howell P. Performance standards and evaluation in IR test collection: Vector-space and other retrieval models. Information Processing and Management [J]. 1997, 33(1).
7William F.Sharpe, Gordon J.Alexander, Jeffery V.Bailey. Investments, the fifth edition. Prentice-Hall, 1995.
8H Markowitz. Portfolio Selection. The Journal of Finanee. 1952.
9William F.Sharpe. Capital Asset Prices: A Theory of Market Equilibrium under Conditions of Risk. The Journal of Finace. 1964.
