In the early 20th century, the Lithuanian linguist Kazimieras Būga showed that essentially all names in the upper Nemunas and upper Dnieper basins were Baltic.[2] In 1962, the Russian linguists Vladimir Toporov and Oleg Trubachyov, in their work, the "Linguistic analysis of the hydronyms of the Upper Dnieper region" (Russian: Лингвистический анализ гидронимов Верхнего Поднепровья), demonstrated that more than a thousand names in the Dnieper basin were of Baltic origin, due to their morphology and etymology.[3]