You need to be a bit more flxible with the spelling. For example, I would spell it "Vasiliy" and not Vasili, Fyodr vs Feodor. Also, Boris I is the same as Boris Godunov. Might also include the houses (Rurikovich, Godunov, Shuysky, Vasa, Romanov). For a challege, maybe include the False Dmitri's. :-)