Paris, Bibliothèque nationale de France, MS lat. 9389 = Echternach Gospels
McNamara, Martin, “The Echternach and Mac Durnan Gospels: some common readings and their significance”, Peritia 6–7 (1988): 217–222.
Stevick, Robert D., “The Echternach Gospels’ evangelist-symbol pages: forms from the ‘two true measures of geometry’”, Peritia 5 (1986): 284–308.  
Each of the rectilinear frames enclosing the evangelist symbols in the Echternach Gospels (Paris, Bibliothèque nationale, MS lat. 9389) can be reconstructed easily, accurately and completely from a single dimension – its width – by using only the draughtsman’s straight-edge and dividers. In the derivational process for these designs can be recognized intellectually the commodulation that otherwise can be only partially intuited. The methods of the construction represent a geometrical inventiveness and depth of understanding of proportion that is paradigmatic for the finest art of early Insular framed crosses and evangelist symbols.

Results for Paris, Bibliothèque nationale de France, MS lat. 9389 (1)