There is great controversy whether this work, 297b for flute, oboe, horn and bassoon, is the same as KAnh. C14.01, another sinfonia concertante in E-flat major for clarinet, oboe, horn and bassoon, which is "Mozart-sounding", but of contested authenticity. Abert 2007, p. 504, n. 56. Abert, Hermann (2007). Eisen, Cliff (ed.). W. A. Mozart. Translated by Spencer, Stuart. Yale University Press. ISBN978-0-300-07223-5. Retrieved 2 August 2017.
A full copy of this letter is to be found in Otto Erich Deutsch, Mozart. A Documentary Biography (2d edition: London, 1966), pp. 56–57. The letter is shown in the Google version of Deutsch's book Letter of Grimm, 15 July 1766 on the visit of the Mozarts in Paris, 10 May – 9 July 1766. This whole letter by Grimm is a remarkable tribute to young Mozart's prodigious abilities. It rivals the famous testimony of 1770 that Daines Barrington sent to the Royal Society about his examination of Mozart in June 1764, which is also online.