???????????????Brennan and Schwartz(1977)?Ingersoll(1977)???????????(?????)????????????????????Brennan and Schwartz(1979,1980,1988)??????????????????????????????????????
https://www.powershow.com/view4/6e0167-MGUzM/Brennan_and_Schwartz_1977_Ingersoll_1977_Brennan_and_Schwartz_1979_1980_1988_powerpoint_ppt_presentation
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