Thaddäus Ertel, a surgeon (Feldscher), and his wife Anna Maria settled in the Volga German colony of Volmer on 18 July 1766. They are recorded there on the 1767 census in Household No. 15.
In 1796, Johann Georg Ertel moved from Volmer to Neu-Kolonie.
The 1767 census records that Thaddäus Ertel came from the German village of Rothenburg.
- 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): Nk05, Vm27, Vm32, Mv2944.
- Pleve, Igor. Einwanderung in das Wolgagebiet, 1764-1767 Band 4 (Göttingen: Göttinger Arbeitskreis, 2008): 288.