Question: What is the name of the author who wrote a series of two science fiction novels, about beings who have taken on the roles of the Greek gods, which makes references to a novel written by a Russian author known by the pen name Vladimir Sirin?
Sentence (from "The Gift (Nabokov novel)"): The Gift (Russian: Дар, "Dar" ; ISBN  ) is Vladimir Nabokov's final Russian novel, and is considered to be his farewell to the world he was leaving behind.
Relevant evidence: No