Research: Pen Flourishing and Puzzle Initials

I spent most of June and July looking for more information on pen flourishing and puzzle initials, but I found that there's a rather large void of information on these things even tho they turn up very often after the 12th Century.  I eventually luck across a mention of a thesis on 13th Century Pen Flourishing that lead to a book based on that thesis, but that's been it so far.

The book is The Analysis of Pen Flourishing in Thirteenth-century Manuscripts, by Sonia Scott-Fleming.

The book did help and I used Scott-Fleming's illustrations as a bases for the ones I included in the handout I created for the local Scribal guild class.  The class went well and next month's class should be on puzzle initials.  So currently I'm looking through hundreds of images of puzzle initials trying to see similarities and then grouping those.  I'm hoping that it will turn out as well as the illustrations in the Pen flourishing handout did.