Question: In which year was the first of the vampire-themed fantasy romance novels for which The Twilight Saga: The Official Illustrated Guide serves as a spin-off encyclopedic reference book first published?
Sentence (from "The Twilight Saga: The Official Illustrated Guide"): The Twilight Saga: The Official Illustrated Guide (previously titled The Official Guide) is a spin-off encyclopedic reference book for the "Twilight Saga" book series, written by Stephenie Meyer and was released on April 12, 2011.
Relevant evidence: Yes