(2008) marked his return to the non-Discworld children's novel, and this was followed in 2012 by Dodger, a children's novel set in Victorian London. On 21 November 2013 Doubleday Children's released Pratchett's Jack Dodger's Guide to London. Pratchett also wrote a popular five-book children's series featuring trainee witch Tiffany Aching and taking place in his Discworld universe, beginning with The Wee Free Men in 2003. In September 2014 a collection of children's stories, Dragons at Crumbling Castle, written by Pratchett, and illustrated by Mark Beech, was published. This was followed by another collection, The Witch's Vacuum Cleaner, also illustrated by Mark Beech, in 2016. A third volume, Father Christmas's Fake Beard, was released in 2017. A fourth and final collection, The Time-travelling Caveman, was released in September 2020. Collaborations and contributions The Unadulterated Cat (1989) is a humorous book of cat anecdotes written by Pratchett and illustrated by Gray Jolliffe. Digital Dreams, edited by David V Barrett (1990), contains the science fiction short story "#ifdefDEBUG + "world/enough" + "time". More Tales from the Forbidden Planet (1990, edited by Roz Kaveney) includes the short story "Hollywood Chickens" with an illustration by Gilbert Shelton. Good Omens, written with Neil Gaiman (1990) After the King: Stories In Honor of J.R.R. Tolkien edited by Martin H. Greenberg (1992) contains "Troll Bridge", a short story featuring Cohen the Barbarian. This story was also published in the compilation The Mammoth Book of Comic Fantasy (2001, edited by Mike Ashley). Now We Are Sick, written by Neil Gaiman and Stephen Jones (1994), includes the poem called "The Secret Book of the Dead" by Pratchett. The Wizards of Odd, a short-story compilation edited by Peter Haining (1996), includes a Discworld short story called "Theatre of Cruelty". The Flying Sorcerers, another short-story compilation edited by Peter Haining (1997), starts off with a Pratchett story called "Turntables of the Night", featuring Death (albeit not set on Discworld, but in our "reality"). Legends, edited by Robert Silverberg (1998), contains a Discworld short story called "The Sea and Little Fishes". The Ultimate Encyclopedia of Fantasy, edited by David Pringle (1998), has a foreword by Pratchett. The Leaky Establishment, written by David Langford (1984), has a foreword by Pratchett in later reissues (from 2001). Meditations on Middle-Earth, an anthology of essays on Middle Earth compiled by Karen Haber, contains Pratchett's essay "Cult Classic" (2002) Once More* With Footnotes, edited by Priscilla Olson and