Jakob Schäfer and his sister Margaretha settled in the Volga German colony of Mariental. Their widowed mother had remarried to Heinrich Ulrich Telf and they are all recorded on the 1767 census of Mariental in Household No. 20.
- Mai, Brent Alan. 1798 Census of the German Colonies along the Volga: Economy, Population, and Agriculture (Lincoln, NE: American Historical Society of Germans from Russia, 1999): Mt67.
- Pleve, Igor. Einwanderung in das Wolgagebiet, 1764-1767 Band 3 (Göttingen: Göttinger Arbeitskreis, 2005): 100.