In the Advanced Keyword Search box immediately below do the following:

1.  Click on the dropdown arrow to the left of the first search window and select Subject.

2.  Enter the name of a country in the first window, such as Nigeria.

3.  Find Year below the search windows and enter a date range, for example, 2008 and 2014.

4.  Click on Submit.

The search above will result in over 103 hits.  To focus your search add a term in the second search window, such as: politic*.  The asterisk is a truncation symbol that will get you politics and political.  This search will result in 55 hits. 

A special division of the Library of Congress produces reports at the request of members of Congress and congressional committees.  Search for those in the public domain here.  Start by entering the name of a country.

CRS Reports