Was he really the first person who published this? You mentioned it to us back in January 2020, but I'm not sure what your source was.
Wikipedia. (German version) Which names both of Bronisch's books in as its sources, so that figures. Mind you, that entry says that a historical novel "Der Meister von Sanssouci" (which is actually about Knobelsdorff the architect) by Martin Stade from 1971 - thus predating Bronsich's doctoral theses by decades - already includes a scene where Manteuffel tells someone else Fritz plagiarized the name. So Bronisch is not the first one to come up with that theory. Martin Stade also wrote a novel "Der König und sein Narr" about Gundling which is credited with changing a part of the reading public's mind about Gundling and which I've been meaning to read for a while.
Re: His Name is Diable. Le Diable: Bad Times
Wikipedia. (German version) Which names both of Bronisch's books in as its sources, so that figures. Mind you, that entry says that a historical novel "Der Meister von Sanssouci" (which is actually about Knobelsdorff the architect) by Martin Stade from 1971 - thus predating Bronsich's doctoral theses by decades - already includes a scene where Manteuffel tells someone else Fritz plagiarized the name. So Bronisch is not the first one to come up with that theory. Martin Stade also wrote a novel "Der König und sein Narr" about Gundling which is credited with changing a part of the reading public's mind about Gundling and which I've been meaning to read for a while.