"John VI of Anhalt-Zerbst (Zerbst, 24 March 1621 – Zerbst, 4 July 1667), was a German prince of the House of Ascania and ruler of the principality of Anhalt-Zerbst.
He was the only son of Rudolph, Prince of Anhalt-Zerbst, by his second wife Magdalene, daughter of John VII, Count of Oldenburg." - (en.wikipedia.org 30.01.2020)