The New Cambridge Modern History
There is a bibliographical guide to the reformation in the following article on Themelios.
https://ref.ly/logosres/themelios02-2;ref=Page.p_53;off=104
In the section on references works all of the volumes recommended are available in Logos format except for "The New Cambridge Modern History" Volume on the Reformation.
I found 13 of the 14 volumes in this set, including the volume on the reformation are available on the Internet Archive
https://archive.org/details/iB_CMH
The volume that is missing is the final volume which is and Atlas. The Atlas from the older set (The Cambridge Modern History) is available on this site.
For complete list of volumes in this set:
https://en.wikipedia.org/wiki/The_Cambridge_Modern_History
While the newer set is probably a little bit dated now thought this might be of use to some of you, particularly where you find articles refering to this set and want to follow-up on the detail.