Vladimir Olgerdovich was a son of which ruler of medieval Lithuania?
Algirdas Algirdas (Belarusian: Альгерд , Russian: Ольгерд , Polish: "Olgierd" ;  1296  – May 1377) was a ruler of medieval Lithuania. He ruled the Lithuanians and Ruthenians from 1345 to 1377. With the help of his brother Kęstutis (who defended the western border of the Duchy) he created an empire stretching from the present Baltic states to the Black Sea and to within fifty miles of Moscow.
Magnus I, Duke of Mecklenburg Magnus I, Duke of Mecklenburg (1345 – 1 September 1384) was Duke of Mecklenburg from 1383 until his death. Magnus was the third son of Duke Albert II of Mecklenburg and his wife Euphemia of Sweden, the sister of the King Magnus IV of Sweden. Sometime after 1362, he married Elizabeth of Pomerania-Wolgast, daughter of Barnim IV, Duke of Pomerania.