Complex sentence: Ferdinando Galli Bibiena says to have invented it in his treatise "Architettura Civile" (1711), however, it was clearly in use before then, including in the works of Juvarra.
Split into simpler sentences: Ferdinando Galli Bibiena claims to have invented it in his treatise "Architettura Civile" (1711). However, the style was clearly in use before then, including in the works of Juvarra.