4Becker, B. E& Huselid, M.A. (2006) . Strategic Human Resource Man- agement: Where do we go from here?[J]. Journal of Management, 32, 898 - 925.
5CamPello,M.,2003.Capital Struc- ture and Product Market Interactions: Ev- idence from Business Cycles, [J].Joumal of Financial Economics, 68: 353-378.
6CamPello, M., J.R.Graham and C.R.Harvey, 2010, The Real Ef- fects of Financial Constraints : Evidence From a Financial Crisis, [J].Journal of Fi- nancialEconomics, 97: 470-487.
7Gonzalez S. Alvaro. (2007) Who Fears Competition from Informal Firms? Evidence from Latin America. The World Bank Financial and Private Sector Development Enterprise Analysis Unit Policy. [J].Research Worlahg Pa- per, 4316.
8Gutmann, M., Peter, The Sub- terranean Economy, [J].Financial Analy- sis Journal, 1977, 6: 26-31.
9Hadlock, C.J. and J.R.Pierce, 2010, New Evidence on Measuring Fi- nancial Constraints: Moving Beyond the KZ Index, [J].Review of Financial Studies, 23 : 1909-1940.
10Subramony, M., Krause, N., Norton, J., & Bums, G.N. (2008) . The Relationship between Human Re- source Investments and Organizational Performance: A Firm-level Examination of Equilibrium Theory..[J]. Journal of Ap- plied Psychology, 93, 778-788.