R. Nahum Baruch b. Zemah David Guenzburg (1882-1941) was chief rabbi of Jonava and a erudite rabbinical scholar. His two volume work, Mekor Baruch (Kedainiai 1928-31), bears witness to his superb scholarship. R. Guenzburg perished in the Holocaust.

Jonava (Rus. Janovo), town in Lithuania, northeast of Kovno. The town was destroyed by fire in 1905 but was quickly rebuilt. In the spring of 1915 the Jews in Jonava were expelled to the Russian interior, and only part of them returned. The Jewish community numbered 3,000 (60% of the total population) on the eve of the Holocaust. When the Germans occupied the town the Jews were deported to the ghetto in Kaunas (Kovno) where they were murdered.