Outside resources

https://en.wikipedia.org/wiki/Slavic_mythology (jackpot)
(sirins: https://en.wikipedia.org/wiki/Sirin . may use them)
(domovoi: Protective house spirits)
(Likho: One eyed women in black/male goblin. symbol of misfortune and evil)
(vodanoy: male water spirits. might use them as kind of bridge keepers or ferrymen)
(rusalka: water nymphs. red hair. usually vengeful spirits. Might use like drowners)
(mara: Malevolent spirits that strangle people in their sleep) x

https://en.wikipedia.org/wiki/Folklore_of_Russia (Mostly Aesop-ish fables. Animal personalities include witty and somewhat assholish foxes, and dim wolves (dissapointing))

Outside resources

Mythic Russia: Motherland Reborn Machali Machali