sentences:  The autographs, all held by the Jagiellonian Library, Kraków, are dated by his father as having been completed in April (K. 37) and July (K. 39–41) of 1767.Although these works were long considered to be original, they are now known to be orchestrations of sonatas by various German virtuosi.The works on which the concertos are based were largely published in Paris, and presumably Mozart and his family became acquainted with them or their composers during their visit to Paris in 1763–64.