The New Grove Dictionary of Music and Musicians, 2001

Sonata op. 87, cop. 1985

(Ries, Ferdinand; works; piano and one instrument; for fl, pf, 5 sonatas, op. 48, 2 as op. 76, op. 87, op. 169)

introd. de la partitura (This sonata was written 'for the piano forte with a flute accompaniment obligato', the title page also states 'the author has, by the addition of small notes, so arranged this sonata that it may performed without an accompaniment')