Other
Chicago Coin Club: Eight Hundred Years of Roman Coinage
Nearly halfway through this page under the subtitle, "Disintegration of the Monetary System" is a discussion of the monetary collapse and the efforts of subsequent emperors to restore the coinage.
Other
Willamette Coin Club: The Times and Coinage of Diocletian: 284 305 a.d.
A description of the massive job facing Diocletian when he assumed the leadership of the Roman Empire, and how he developed the tetrarchy. There is also information about Roman coinage.