Here’s Ed Dolan:
I see NGDP targeting as the natural heir to monetarist policy prescriptions of the 1960s and 70s.
If we look at the textbook version of monetarism, the point is almost trivial. Textbook monetarism begins from the equation of exchange, MV=PQ, where M is money (M1, back in the day), V is velocity, P is the price level, Q is real GDP, and PQ is NGDP. Next it adds the simplifying assumption that velocity is constant. It follows that targeting a steady rate of money growth is identical to targeting a steady rate of NGDP growth.