http://neobyzantium.com/what-is-a-tetrarchy/

 

ancienthistory.about.com/od/romeempire/g/tetrarchy.htm

 

http://www.ancient.eu/Diocletian/

 

http://www.roman-emperors.org/dioclet.htm

 

http://www.britannica.com/biography/Diocletian

 

http://lightofdesert.blogspot.com/2014/04/the-spread-of-christianity-through.html

 

www.myartprints.co.uk

 

http://uncyclopedia.wikia.com/wiki/Diocletian

 

https://en.wikipedia.org/wiki/Diocletian