Try Steve Keen and his work. He modeled both fixed money and flexible money supply in his dynamical models of finance. You can even download a computer program

Try Steve Keen and his work. He modeled both fixed money and flexible money supply in his dynamical models of finance. You can even download a computer program "Minsky" and try the models yourself. Edit: He is also a proponent of "endogenous theory of money", which basically says that money can be easily created within the system through debt. In essence, "fiat money" is a fundamental property of monetary systems, and not something imposed by governments.