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.
Maria of Vitebsk Maria of Vitebsk (died before 1349) was the first wife of Algirdas, future Grand Duke of Lithuania (marriage took place around 1318). Very little is known about her life. The only child of a Russian prince Yaroslav, Maria was the only heir to the Principality of Vitebsk. After her father's death ca. 1345, Vitebsk fell permanently under control of Algirdas and other Gediminids. Maria gave birth to five sons, all of whom grew up while Algirdas was still only a regional duke in Slavic lands of the Grand Duchy of Lithuania. All five sons were baptized in Orthodox rite and ruled Russian lands giving rise to prominent clans of Russian dukes (Trubetskoy family from Demetrius I Starshy, Czartoryski family from Constantine, Sanguszko family from Fiodor, Belsky and Olelkovich families from Valdimir). After Maria's death, Algirdas married another Russian princess, Uliana of Tver. After Algirdas' death, eldest sons of Maria and Uliana battled over succession rights.