Pôdorys Baziliky San Vitale v Ravenne, Zdroj: <a rel="nofollow" class="external free" href="http://projects.mcah.columbia.edu/medieval-architecture/htm/related/ma_ravenna_vitale_02.htm">http://projects.mcah.columbia.edu/medieval-architecture/htm/related/ma_ravenna_vitale_02.htm</a>, <a rel="nofollow" class="external free" href="https://cluster8.canvas-user-content.com/courses/1084~200544/files/1084~2586135/course%20files/15-Carolingian/Carolingian%20Architecture?download=1&amp;inline=1">https://cluster8.canvas-user-content.com/courses/1084~200544/files/1084~2586135/course%20files/15-Carolingian/Carolingian%20Architecture?download=1&amp;inline=1</a>
Free images on commons: Jackson, Thomas Graham, Encyclopædia Britannica, August Essenwein
Free images on commons: File:Byzantine and Romanesque architecture (1913) (14589723108).jpg, File:1911 Britannica-Architecture-S. Vitale.png, File:Jahrbuch MZK Band 03 - Gewölbesystem - Fig 02 San Vitale zu Ravenna.jpg