Langlé (H.F.M.): Traité d'Harmonie st de Modulation, Paris, chez Naderman, 1793, folio, presentation copy, title signed at foot by the publisher, engraved throughout, contemporary green vellum, gilt borders incorporarting neoclasical motifs, spine gilt, red morocco label on upper cover lettered in gilt: 'À Mlle. Gardel de la Part de l'Auteur' (lightly rubbed). [Corot pp. 107-08; Gregory-Sonneck 146; not in Hirsch or BM (which only has the 1793 edition by Boyer)]