This sub-series comprises handwritten notes by Klenz and the manuscript of the book Giovanni Maria Bononcini of Modena. It provides insights into Klenz's thought process and research undertaken during the book's writing. Additionally, the sub-series includes letters from Klenz's friends related to the book, as well as letters to readers. The supplement index of the book is also documented within this sub-series. It serves as a valuable resource for understanding the intricate details, research, and correspondences surrounding Klenz's work on the book.