I would recommend the following works, which are cited in this earlier answer I wrote on the collapse of the USSR.

Aron, Leon. "The "Mystery" of the Soviet Collapse". Journal of Democracy, April 2, 2006

Brown, Archie. Seven Years that Changed the World: Perestroika in Perspective.

Fitzpatrick, Sheila. "The Soviet Union in Retrospect - Ten Years After 1991" in The Legacy of the Soviet Union.

Hahn, Gordon. Russia's Revolution from Above 1985-2000: Reform, Transition and Revolution in the Fall of the Soviet Communist Regime.

Kotkin, Stephen. Armageddon Averted: The Soviet Collapse, 1970-2000

Nove, Alec. An Economic History of the USSR 1917-1991

Plokhy, Serhii. The Last Empire: The Final Days of the Soviet Union

Service, Robert. The End of the Cold War, 1985-1991. This is mostly a diplomatic history of US-Soviet relations

I'd also recommend Yegor Gaidar's article "The Soviet Collapse: Grain and Oil". Personally I think his theory here is a bit too simplified, and it's worth noting that as Gaidar was Yeltsin's acting Prime Minister who instituted shock therapy, and considering that the US conservative American Enterprise Institute published the article, there's definitely a political agenda to his approach. Still, I wouldn't totally discount it, because these economic trends were real strains on the Soviet economy during the period in question.