"...explain how Ronald Reagan..."
Reagan was actually quite intelligent, but leftists can't stand that idea, so we'll let that one slide.
I have plenty of sources on the Cold War and credit. I filtered out a few I thought you might pay attention to.
Slate article
CBS News
And last but not least:
And while his legacy will forever be marked by the scandals of the Iran-Contra affair, Ronald Reagan's presidency began with the release of the Iran hostages.
While it began with preparations for conflict with a country, the Soviet Union, that he called "The Evil Empire," it will also certainly bear much of history's credit for that country's final decline... and the freedom of Eastern Europe that blossomed in its wake.
