Zappa's oeuvre includes symphonies, trios, sonatas, divertimenti and songs. He wrote many romantic airs, divertimenti, sonatas and dances for the piano forte. These works were called serenades (sera=night), nocturnes, divertimenti, or cassations (from gasse=street). Six Divertimenti, for two flutes and basso continuo, op. No other attested Mozart concerto is homotonal though several of his symphonies and divertimenti are. Other composers of "divertimenti" include Leopold Mozart, Carl Stamitz, Haydn and Boccherini. Though Perger called them nocturnes, some of these are more generally known as divertimenti. It is widely regarded as separate from his other divertimenti. Lasting about 42 minutes, it takes the longest to perform among the divertimenti by Mozart.