Origins of the Universe

Origins of the Universe is a book by (or at least credited to) Oolon Caluphid, which the Doctor was reading around the time of Romana's first regeneration and an encounter with the Daleks. (DW: Destiny of the Daleks)

Behind the Scenes

 * The author Oolon Caluphid is a character in Douglas Adams' The Hitchhiker's Guide to the Galaxy; at the time Destiny of the Daleks was produced, Adams was script editor on Doctor Who and was also preparing the radio series (and later book series) of Hitchhiker's Guide. The reference to Caluphid has raised the question as to whether the Whoniverse and the Hitchhiker's Guide universe either intersect or have commonality. A later reference to Arthur Dent (DW: The Christmas Invasion) was similarly vague. In the real world it's not uncommon for books to be credited to fictional characters (J.K. Rowling wrote several Harry Potter spin-off works in this vein, for instance).