Paul Corby Finney (1999). Seeing Beyond the Word: Visual Arts and the Calvinist Tradition. Wm. B. Eerdmans Publishing. p. 272. ISBN978-0-8028-3860-5. Retrieved 27 January 2013. "... was engaged for Frederick the Great; after 1736 he was attended by, among others, Charles Etienne Jordan (1700- 1745), ... Like Heinrich August de la Motte Fouque (1698-1774), he belonged to the "Rheinsberg Circle," later also joined by ..."
