Primære kilder Herodianus: : The Three Gordians Aurelius Victor: Johannes Zonaras: , utdrag [https://web.archive.org/web/20080521191250/http://www.ancientsites.com/aw/Post/1049415 Alexander Severus to Diocletian: 222–284The Roman Government in BritainTriumph & Tragedy: The Rise and Fall of Rome's Immortal EmperorsDe Imperatoribus RomanisThe Roman Empire from Severus to ConstantineEmperors and Biography'', Oxford University Press. Potter, David Stone (2004): The Roman Empire at Bay, AD 180-395, Routledge.