Who dated Varvara Turkestanova?

Princess Varvara Ilynichna Turkestanova (Russian: Варвара Ильинична Туркестанова; 26 December 1775 – 20 May 1819) was a Russian noblewoman of Georgian origin, known for her affair with Tsar Alexander I of Russia and her correspondence with the French émigré Ferdinand Christin, which describes the Russian court life of the 1810s. She took her own life shortly after giving birth to a daughter, whose father was either Tsar Alexander or her other lover, Prince Vladimir Golitsyn. Her surname is also transliterated in Western European languages as Tourkestanoff, Tourkestanov, or Tourkestanow.