References for Elena (Marfa) Aleksandrovna [r]Potemkina
N. Ikonnikov:
La Noblesse de Russie.
Paris, 1956-196?, Vol. #
A.Tihonova:
The Engelhardt's Family in Russian History in the 17th-20th c..
1er Colloque International de Généalogie, Moskva, 1999