各位朋友，能不能帮我下以下几篇文献，万分感谢！

11、【篇名】Modeling long-runbehavior with the fractional ARIMA model【作者】Fallaw Sowell【网址】http://www.sciencedirect.com/science/article/pii/030439329290016U 12、【篇名】Bivariate GarchEstimation of the Optimal Commodity Futures Hedge【作者】Richard T. ;Robert J.【网址】http://www.jstor.org/sici?sici=0883-7252(1991)6:2<109>2.0.CO;2- 13、【篇名】Hedging effectivenessand minimum risk hedge ratios in the presence of autocorrelation: Foreigncurrency futures【作者】A. F. Herbst;D. D.Kare;S. C. Caples【网址】http://onlinelibrary.wiley.com/doi/10.1002/fut.3990090302/abstract 14、【篇名】Interest-RateVolatility, Basis Risk and Heteroscedasticity in Hedging Mortgages【作者】Hun Y. Park;Anil K.Bera【网址】http://onlinelibrary.wiley.com/doi/10.1111/1540-6229.00420/abstract 15、【篇名】Estimating HedgeRatios【作者】David E. ;William S.【网址】http://www.jstor.org/sici?sici=0046-3892(1986)15:2<34>2.0.CO;2-