He cites "Freakonomics" by Steven D. Levitt and Stephen J. Dubner;
"Fooled by Randomness," Nassim Nicholas Taleb;
"The Black Swan," Nassim Nicholas Taleb
"Capital Ideas Evolving," Peter L. Bernstein
"Inside the Investor's Brain," Richard L. Peterson
He also quotes from "The General Theory of Employment, Interest and Money," by John Maynard Keynes, whom he calls his favorite economist.
Other than Keynes, all these books are recent and show a number of the influences shaping modern economics, such as neuroscience and behavioral psychology. If he successfully integrates these ideas in his book in a way intelligible to the reader, he'll have a powerful book. UPDATE: El-Erian's book has to be on this list, and probably should be first (Big Think Breakdown on When Markets Collide). He's got the best analysis I've yet seen or heard on just what's going on and what the risk factors are.