From Mark Scousen in "Making Modern Economics"

Ironically, by the time of the thirteenth edition [of Paul Samuelsons popular economics textbook], right before the Berlin Wall was torn down, Samuleson and Nordhaus confidently declared, "The Soviet economy is proof that, contrary to what many skeptics believed [a reference to Mises and Hayek], a socialist command economy can function and even thrive."  From this online excerpt.