Widow Anna Margaretha Petri and her son Johannes are recorded on the 1775 census of Beideck in Household No. 40 along with orphan Johannes Heinrich Ostermüller. The 1775 census of Beideck does not record a relationship between the Petri and Ostermüller families.
- 1775 Census of Beideck (No. 40).
- 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): Bd70.