Rosenthal, E.: The Invention of the Columnar Device of Emperor Charles V at the Court of Burgundy in Flanders in 1516. In: Journal of the Warburg and Courtauld Institutes 36 (1973), S. 198-230
[BibTeX] 

Rosenthal, E.: Plus ultra, non plus ultra, and the Columnar Device of Emperor Charles V. In: Journal of the Warburg and Courtauld Institutes 34 (1971), S. 204-228
[BibTeX]