Мафия 89. Nemesis

I tried to decipher the previous clues; how well I succeeded is up to you to judge.
Book Knight -> a recently opened bookstore called "Book Knight" in the city of Frankfurt am Main -> which is a major city in Germany -> Göttingen and its `school` (Göttingen school), to which Emmy Noether belonged, who derived a theorem stating that every continuous symmetry of a physical system corresponds to some conservation law -> a conservation law in Yashchur's profile.