Pupienus and Balbinus
- Wikipedia article about the lives of these two Roman Emperors.
- http://en.wikipedia.org/wiki/Pupienus

The History of the Decline and Fall of The Roman Empire - Vol 1 - Chapter VII Part II
- From Edward Gibbon's "Decline and Fall of The Roman Empire," details the co-rule of the empire by Balbinus and Pupienus.
- http://www.worldwideschool.org/library/books/hst/roman/TheDeclineandFallofTheRomanEmpire-1/chap19.html

Decimus Caelius Calvinus Balbinus
- Biography of the life and brief reign of the Roman Emperor Balbinus.
- http://www.roman-empire.net/decline/balbinus.html