Question: The Toccata and Fugue in D minor, BWV 538, is an organ piece by Johann Sebastian Bach, like the better-known BWV 565, the Toccata and Fugue in D minor, BWV 565, is a piece of organ music written, according to its oldest extant sources, by who?

full_context: Document 1: Prelude and Fugue in E minor, BWV 548: Prelude and Fugue in E minor, BWV 548 is a piece of organ music written by Johann Sebastian Bach sometime between 1727 and 1736, during his time in Leipzig. The work is sometimes called "The Wedge" due to the tonal structure of the fugue theme.
Document 2: Toccata and Fugue in D minor, BWV 565: The Toccata and Fugue in D minor, BWV 565, is a piece of organ music written, according to its oldest extant sources, by Johann Sebastian Bach. The piece opens with a toccata section, followed by a fugue that ends in a coda. It is one of the most famous works in the organ repertoire.
Document 3: Prelude in C-sharp minor (Rachmaninoff): Prelude in C-sharp minor (Russian: Прелюдия ), Op. 3, No. 2, is one of Sergei Rachmaninoff's most famous compositions. It is a ternary (ABA) prelude for piano in C-sharp minor, 62 bars long, and part of a set of five pieces entitled "Morceaux de fantaisie"; and also known as "The Bells of Moscow" since the introduction seems to reproduce the Kremlin's most solemn carillon chimes.
Document 4: Capriccio on the departure of a beloved brother: The Capriccio on the departure of a beloved brother (Italian: Capriccio sopra la lontananza del suo fratello dilettissimo), BWV 992, is an early work by Johann Sebastian Bach, possibly modeled on the Biblical Sonatas of Johann Kuhnau. The story that Bach performed it at age nineteen when his brother Johann Jacob left to become an oboist in the army of Charles XII in Sweden is questionable.
Document 5: Toccata, Adagio and Fugue in C major, BWV 564: Toccata, Adagio, and Fugue in C major (BWV 564) is an organ composition by Johann Sebastian Bach. As is the case with most other organ works by Bach, the autograph score does not survive. The earliest manuscript copies were probably made in 1719–1727. The title of the piece in these copies is given, as expected of organ literature of the time, simply as "Toccata in C major" (or more precisely, "Toccata ped: ex C" in one source and "Toccata ex C♮ pedaliter", referring to the obbligato pedal part). The piece is an early work, probably composed in the mid-to-late Weimar years, i.e. 1710–1717. It shares some similarities with other toccatas composed around the same time, such as BWV 538, BWV 540, and others: all show the influence of concerto style and form.
Document 6: Johann Sebastian Bach: Johann Sebastian Bach (31 March [O.S. 21 March] 1685 28 July 1750) was a German composer and musician of the Baroque period. He is known for instrumental compositions such as the "Brandenburg Concertos" and the "Goldberg Variations", and vocal music such as the "St Matthew Passion" and the Mass in B minor. Since the 19th-century Bach Revival he has been generally regarded as one of the greatest composers of all time.
Document 7: Toccata and Fugue in F major, BWV 540: The Toccata and Fugue in F Major, BWV 540 is an organ work written by Johann Sebastian Bach. The toccata is thought to be written after 1714, and the fugue before 1731. It is thought by some that Bach joined together two previously separate pieces to create this work.
Document 8: Fugue in G minor, BWV 578: Fugue in G minor, BWV 578, (popularly known as the "Little Fugue"), is a piece of organ music written by Johann Sebastian Bach during his years at Arnstadt (1703–1707). It is one of Bach's best known fugues and has been arranged for other voices, including an orchestral version by Leopold Stokowski.
Document 9: Organ concerto: An organ concerto is a piece of music, an instrumental concerto for a pipe organ soloist with an orchestra. The form first evolves in the 18th century, when composers including Antonio Vivaldi, Johann Sebastian Bach and George Frideric Handel wrote organ concertos with small orchestras, and with solo parts which rarely call for the organ pedal board. During the Classical period the organ concerto became popular in many places, especially in Bavaria, Austria and Bohemia (whether called there a concerto, pastorella, or sonata), reaching a position of being almost an integral part of the church music tradition of "jubilus" character. From the Romantic era fewer works are known. Finally, there are some 20th- and 21st-century examples, of which the concerto by Francis Poulenc has entered the basic repertoire, and is quite frequently played.
Document 10: Great Fantasia and Fugue in G minor, BWV 542: The Great Fantasia and Fugue in G minor, BWV 542, is an organ prelude and fugue by Johann Sebastian Bach. It acquired that name to distinguish it from the earlier Little Fugue in G minor, which is shorter. This piece is not to be confused with the Prelude and Fugue in A minor, which is also for organ and also sometimes called "the Great".
Document 11: Prelude and Fugue in A minor, BWV 543: Prelude and Fugue in A minor, BWV 543 is a piece of organ music written by Johann Sebastian Bach sometime around his years as court organist to the Duke of Saxe-Weimar (1708–1717).
Document 12: Toccata and Fugue in D minor, BWV 538: The Toccata and Fugue in D minor, BWV 538, is an organ piece by Johann Sebastian Bach. Like the better-known BWV 565, BWV 538 also bears the title "Toccata and Fugue in D Minor", although it is often referred to by the nickname Dorian – a reference to the fact that the piece is written without a key signature – a notation that is uncommon today and leads one to assume the Dorian mode.
Document 13: Fantasia and Fugue in C minor, BWV 562: The Fantasia and Fugue in C minor, BWV 562 is a relatively short piece written for the organ by Johann Sebastian Bach. Bach began the composition during his time in Weimar, and an unfinished fugue, probably by Bach, was added in his later life. The piece features a heavily appoggiatura-laden harmony.
Document 14: Toccata (Prokofiev): The Toccata in D minor, Op. 11 is a piece for solo piano, written by Sergei Prokofiev in 1912 and debuted by the composer on December 10, 1916 in Petrograd. It is a further development of the toccata form, which has been used by composers such as Johann Sebastian Bach and Robert Schumann. Other composers of well-known toccatas include Maurice Ravel, Dmitri Kabalevsky and Aram Khachaturian.
Document 15: Prelude and Fugue in C-sharp minor, BWV 849: The prelude and fugue in C-sharp minor, BWV 849, is a pair of keyboard compositions by Johann Sebastian Bach. It is the fourth prelude and fugue in the first book of "The Well-Tempered Clavier", a series of 48 preludes and fugues by the composer.
ground_truth: Johann Sebastian Bach