2Korajczyk R A,Levy A. Capital structure choice:macroeconomic conditions and finan cial constraints [J] Journal of Financial Economics, 2003,68 (1):75-109.
3Fama E F, French K R. Disappearing divi-dends: changing firm characteristics or lower propen- sity to pay? [J]. Journal of Financial economics, 2001,60(1) : 3-43.
4Opler T, Pinkowitz L, Stulz R, et al. The deter- minants and implications of corporate cash holdings [J ]. Journal of Financial Economics, 1999,52 (1) : 3-46.