His chapter on all the builders, including Knobelsdorff, your wiki quote, and the above details, is here.
The volume is now in the library.
Along with a completely unrelated work that mentions Fredersdorf: a 2010 Harvard dissertation by Ellen Exner on Fritz and music, 1732-1756. Apparently, J.S. Bach dedicated a sonata to Fredersdorf! (I have already spotted two chronological problems in this dissertation--Fritz was 18, not 17, in the summer of 1730, and Fredersdorf married in 1753, not 1751--but one hopes the author makes up for it with other data that's accurate.)
Re: Book review I: Der Meister von Sanssouci - Fredersdorf and historical footnotes
The volume is now in the library.
Along with a completely unrelated work that mentions Fredersdorf: a 2010 Harvard dissertation by Ellen Exner on Fritz and music, 1732-1756. Apparently, J.S. Bach dedicated a sonata to Fredersdorf! (I have already spotted two chronological problems in this dissertation--Fritz was 18, not 17, in the summer of 1730, and Fredersdorf married in 1753, not 1751--but one hopes the author makes up for it with other data that's accurate.)