"Barbara Sophia of Brandenburg (16 November 1584 – 13 February 1636) was duchess of Württemberg by marriage to Duke John Frederick of Württemberg and acted as regent of the Duchy of Württemberg for their minor son, Duke Eberhard III of Württemberg, in 1631-1633. She was the daughter of the Catherine of Küstrin (1549–1602) and Elector of Joachim Frederick of Brandenburg." - (en.wikipedia.org 29.01.2020)
