However, two-movement layouts also occur, a practice Haydn uses as late as the 1790s. There was also in the early Classical period the possibility of using four movements, with a dance movement inserted before the slow movement, as in Haydn's Piano sonatas No. 6 and No. 8. Mozart's sonatas were also primarily in three movements. Of the works that Haydn labelled "piano sonata", "divertimento", or "partita" in Hob XIV, seven are in two movements, thirty-five are in three, and three are in four; and there are several in three or four movements whose authenticity is listed as "doubtful." Composers such as Boccherini would publish sonatas for piano and obbligato instrument with an optional third movement—–in Boccherini's case, 28 cello sonatas.