With the Federal Reserve having expended almost all monetary tools now, the only major course of action left, short of directly buying ETFs, is more quantitative easing, said Danielle DiMartino Booth, CEO of Quill Intelligence."If you're at the zero bound, and the Fed has been at the zero bound for much of the last decade, if you're at the zero bound, the only discussion you're really having is how do we get more product, how do we get more [quantitative easing]," Booth told Kitco News.Booth was a former advisor with the Federal Reserve Bank of Dallas from 2006 to 2016, working with Richard Fisher. She is author of "Fed Up: An Insider's Take on Why the Federal Reserve is Bad for America."