5[12]COWEN T. Public Goods and Market Failures[M]. New Brunswick: Transaction Publishers, 1992.115.
6[13]CLAUDIA K, FRANS van W. Conditional cooperation and voluntary contributions to public goods[J]. Scandinavian Journal of Economics, 2000,102(1):23-39.
7[14]KEVIN S, SANDLER T. Collective goods, common agency and third-party intervention[J]. Bulletin of Economic Research, 2004, 56(1):3307-3378.
8[16]MARK B, RHODES R A, WELLER P. Comparative governance: prospects and lessons[J]. Public Administration, 2003, 81(1):191-210.