context: The first mention of the trade fair settlement Swedish: Systerbäck at the mouth of the Sestra River is found in the Swedish chronicles of 1643 [32]. The name of the city is based on the hydronym Sister (from Finnish: Siestarjoki - "Blackcurrant River") [33]. The Finnish (Siestarjoki) and Swedish (Systerbäck) forms of the name of the city now coincide with the name of the river.
question: In honor of which the city of Sestroretsk got its name?
answers.text: hydronym Sister (from Finnish: Siestarjoki - "Blackcurrant River")