This is the title of a speech by St Louis Fed President- James Bullard. He was one of the leading proponents of QE2 or buying of government bonds. Press release here and slides here.
He explains QE2 in five pieces (not sure about they being easy):
St Louis Fed economists have a short note on the topic.
Simona Cociuba of Dallas Fed has a nice short note on the topic. Just like this crisis has given IMF qa new lease of life so is the case for IMF’s reserve currency — Special Drawing Rights.