Dubravka is related to 'Dubrava'(Oak Grove), which is related to 'Dub'=Oak Tree; Celtic= Dubh, who dwelled on Balkan Peninsula prior to arrival of South Slavs. There are occurrences of other names and words in South Slavonic languages related directly to Celts, but I shall not go into this area. Also, often has been thought that ?Dub? has a very close ?sharing? meaning with ?Drevno?=very old, ancient, and yet we know that ?drvo?=tree, wood can be appendage to the same family.
DKT
PhD Linguistics