A personal example illustrates the importance of understanding Jewish given names in Jewish genealogical research. My grandfather had a first cousin, who was listed by various names in different sources. The first document, illustrated here, is his 1881 civil marriage registration from Nowogród, Lomza Guberniya, Poland, which lists him (in Cyrillic letters) as "Leibka Gershkevich". In Russian, this means "Leib, son of Hersh".