A list of individuals who emigrated from the Bergwinkel region during 1766 states that Kilian Bretthauer from Sterbfritz went to Russia. He was baptized on 22 Apr 1732 in Sterbfritz, son of Johannes Bretthauer. He married Anna Barbara, the daughter of Adam Johann, on 17 May 1757, in Sterbfritz. Sterbfritz is southeast of Schlüchtern.
The couple settled in Walter in 1767 and are reported there in First Settler's List #3.
Seven Bretthauer families from Walter relocated to Brunnental in 1859, 1863, 1864
Parish records of Sterbfritz on Archion.de
Pleve, Igor. Einwanderung in das Wolgagebiet, 1764-1767 Band 4 (Göttingen: Nordost-Institute, 2008): p. 296
Russland-Auswanderer aus dem Bergwinkel um 1766 und die Spurensuche nach ihrer Rückkehr im 20. Jahrhundert (website accessed 30 Nov 2020 and no longer online). https://www.schluechtern.de/schluechtern-unsere-stadt/geschichte/russland-auswanderer-aus-dem-bergwinkel-um-1766.html
Hein, Maggie, translator. Brunnental, Russia Communion Register (1870-1884) Volume 1 (Lincoln, NE: American Historical Society of Germans from Russia, 2020)