(in French)Le brigandage de la musique italienne, s.n., 1777, pp. 38-39 (accessible online at Gallica - B.N.F.).
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Letter to Giovanni Claudio Pasquini, 29 June 1748, in Raccolta di lettere scientifiche, familiari, e giocose dell'abate Pietro Metastasio romano, Rome, at the expence of Pietro Puccinelli, s.d., III, p. 338 (accessible online at Google Books).
(in German)Herrn Johann Joachim Quantzens Lebenslauf, von ihm selbst entworfe, in Friedrich Wilhelm Marpurg, Historisch-Kritische Beyträge zur Aufnahme der Musik, Berlin, Schützens Witwe, 1755, I, p. 227 (accessible online at Commons).