PAIS
Contains references to more than 460,000 journal articles, books, government documents, statistical directories, grey literature, research reports, conference reports, publications of international agencies, microfiche, Internet material, and more.

PolicyFile
Updated weekly with additions of approximately 250 records per week, the database currently includes over 91,000 records from 1995 to current of  foreign and domestic policy papers produced by an impressive and growing number of nongovernmental agencies, research institutes, and think tanks in the U.S.

CRS Reports (in Proquest Congressional)
Congressional Research Services (CRS) provides non-partisan reports on all major policy issues. 

GAO Reports
Government Accountbility Office provides the government and general public non-partisan information on all major government programs and policy issues. The archive of GAO reports are included in Hein Online, a library database. 

CQ Press Public Policy Collection
The database provides analysis, statistics and primary sources on major policy issues. 

CQ Researcher Plus Archive
CQ Researcher provides regular reports on all major issues in politics and international affairs.

Chatham House Archive
An archive of papers published by the UK think tank. For the current publications, go to the Chatham House website.

China Economy, Public Policy, and Security (Chinese) 
Chinese think tank reports.