JewishGen
JewishGen remains the best site for databases in English of persons from the past connected to Dubova.
Russian archives
Archive: Jewish Towns / Kyiv Governorate
A massive website in Ukrainian holding mostly original Russian documents, many from the 19th and early 20th centuries, with categories for Uman district and Cherkasy oblast.
Holocaust data
Yad Vashem—The World Holocaust and Remembrance Center
United States Holocaust Memorial Museum