|"Is this all real? Or has this been happening inside my head?"
The subject of this article is a real-life person, group, company, product, or creative work that has been mentioned "in-universe" in a canon source. The Harry Potter Wiki is written from the perspective that all information presented in canon is true (e.g., Hogwarts really exists), and, as such, details contained in this article may differ from real world facts.
The Call of the Wild is an adventure novel by Jack London about a dog that is stolen from his owners and forced to become a sled dog during the Klondike Gold Rush. The bookshop Screed & Sons had several copies of The Call of the Wild.