The Adventures of Ugo is one of the books donated by William Minerva with a hidden message on its ex libris. This book portrays the fantasy-like adventure of a young man Ugo and lemur friend Marvine, which was coincidentally found to be parallel to what the orphans have experienced during their escape from Grace Field House in the Demon World.

The Snakes of Alvar Pena refers to the Bloodsucker Trees.