According to my father, Herman D. Plavnick (via my mother), Samuel Plavnick and Esther (Pessin) Plavnick, came from Pinsk and Minsk, Belarus (also known as White Russia), then an oblast, or region, of Tsarist Russia. Though I'm not sure who was from where, I believe Sam was from Pinsk and Esther from Minsk. As Sam was born in Vitebsk, Belarus, perhaps he (or Esther) later lived in Minsk.
The city of Minsk, capital of today's Republic of Belarus has an several english language web sites, indivdual and civic. One of these could be an information source, although Minsk was almost totally destroyed during the war and it's questionable if any pre-war records survived.
Incidentally, although the Plavnick site lists Esther's maiden name as "Peskin", I have a letter from my Aunt Thresa, who was married to her brother Joseph, and she spells it "Pessin."