Further information on the series' mythology and production have been detailed through print. Official companion guides for the first six seasons have been released (, , , , , ), all written by Nicholas Knight and published by Titan Books. Two additional guides written by Alex Irvine, "The "Supernatural" Book of Monsters, Spirits, Demons, and Ghouls" () and "John Winchester's Journal" (), have been published by It Books. Irvine's books function as resource guides that contain illustrations and detailed descriptions of the supernatural creatures the Winchester family has encountered, giving additional background on creatures and mythology featured on the show. Premiering on November 27, 2007, was the Official "Supernatural" Magazine. Published by Titan Magazines, it contains series information and exclusive cast and crew interviews. It Books published "Supernatural: Bobby Singer's Guide to Hunting" by David Reed on September 6, 2011 (), sharing all the knowledge that the character Bobby Singer had to share about hunting, the Winchesters, and other knowledge he picked up over the years dealing with the elements of the supernatural.