The Piano Sonata No. 15 in C major, Hob. XVI/15, is an arrangement for solo keyboard of the 1st, 3rd and 4th movements of the Divertimento in C (Hob. II/11)[1][2] by Joseph Haydn. This sonata is now considered spurious.[3]
^Landon, H.C. Robbins (1980). Haydn: Chronicle and Works, Vol 1: The Early Years 1732-1765. London: Thames and Hudson. p. 703.