Бах Fantasia and Fugue in C minor, BWV 562

The Fantasia and Fugue in C minor, BWV 562 is a piece for organ written by Johann Sebastian Bach. He began the composition of the Fantasia during his Weimar period: the fugue was added later, around 1745. It is discussed if Bach himself added the Fugue to the original fantastia or if one of his sons did it