9Stiglitz Joseph E, Weiss Andrew. Credit rationing in markets with imperfect information [ J ]. American Economic Review, 1981,71 (3) :393 -410.
10Berger A N, Udell G F. The Economics of small business finance: The role of private equity and debt markets in the financial growth cycle[ J].Journal of Banking and Finance, 1998,22:613 -673.