Prometric recommends these books:
The Rise and Fall of the Soviet Union*
Gilbert, Martin. 
Soviet History Atlas. London:
Routledge & Kegan Paul Ltd., current edition.
Hosking, Geoffrey. 
The First Socialist Society: A
History of the Soviet Union from Within. Cambridge,
MA: Harvard University Press, current edition.
Kort, Michael. 
The Soviet Colossus: History and
Aftermath. Armonk, NY: M.E. Sharpe, current
edition.
McCauley, Martin. 
The Soviet Union 1917-1991.
New York, NY: Longman, current edition.
Nove, Alec. 
An Economic History of the USSR
1917-1991. New York, NY: Penguin Books, current
edition.
Thompson, John M. 
A Vision Unfulfilled: Russia
and the Soviet Union in the Twentieth Century.
Lexington, MA: D.C. Heath and Company, current
edition.
Treadgold, Donald W. 
Twentieth-Century Russia.
San Francisco, CA: Westview Press, current edition.
Western Europe Since 1945^
Black, Cyril, Jonathan Helmreich, Paul Helmreich,
Charles Issawi, and A James McAdams. 
REBIRTH:
A History of Europe Since World War II. Boulder,
CO: Westview Press, Inc., current edition.
Edited by Joseph Colomer. 
Political Institutions in
Europe. New York, NY: Routledge, current edition.
George, Stephen. 
Politics and Policy in the
European Union. New York, NY: Oxford University
Press, current edition.
Lane, Jan-Erik and Svante Ersson. 
European
Politics: An Introduction. Thousand Oaks, CA: Sage
Publications, current edition.
Hancock, Donald, David Conradt, B. Guy Peters,
William Saftan and Raphael Zariski. 
Politics in
Western Europe: Introduction to the Politics of the
United Kingdom, France, Germany, Italy Sweden,
and the European Union. Chatham, NJ: Chatham
House Publishers, current edition.
Nelson, Brent and Alexander Stubb. 
The European
Union: Readings on the Theory and Practice of
European Integration. Boulder, CO: L. Rienner
Publishers, current edition.
Piening, Christopher. 
Global Europe: The European
Union in World Affairs. Boulder, CO: Rienner
Publishers, current edition.
Rose, Richard. 
What is Europe?: Dynamic
Perspective. New York, NY: Longman, current
edition.
Sperling, James and Emil Kirchner. 
Recasting the
European Order: Security Architectures and
Economic Cooperation. New York, NY: Manchester
University Press, current edition.
Steiner, Jurg. 
European Democracies. New York,
NY: Longman, current edition.
Urwin, Derek. 
Western Europe Since 1945: A
Political History New York: Longman, current
edition.
Wood, David and Birol Yesilada. 
The Emerging
European Union. White Plains, NY: Longman,
current edition.
I know there is quite a bit there, but hopefully it's a start in the case you haven't seen the official recommendations from the test creator. Below are the documents I got the information from, if you want to read more.
Good Luck!!!
*
http://www.getcollegecredit.com/download...0Union.pdf
^
http://www.getcollegecredit.com/download...201945.pdf