1. Beckett P. SEC Hits Barrier to Muni-Bond Reform. The Wall Street Journal 1997. 16 May 1997, A13.
2. Bradsher K. SEC Curbs Donations by Bond Dealers. The New York Times 1994. 7 April 1994 D1.
3. Institutional Environment and Sovereign Credit Ratings;Butler;Financial Management,2006
4. Butters R. Depken C. A. LaFountain C. L. Corruption and Creditworthiness: Evidence from Sovereign Credit Ratings. 2006. SSRN Working Paper Series (http://ssrn.com/abstract=899414).
5. Differences of opinion and selection bias in the credit rating industry