The Hitchhiker's Guide to the Galaxy (in-universe)

You may be looking for the real-world series.

The Hitchhiker's Guide to the Galaxy was a series of novels written by Douglas Adams. (PROSE: Doctor Who: The Encyclopedia ^[+]Loading...{"name":"\"encyclopedia\"","page":"16","ed":"2011 reprint","1":"Doctor Who: The Encyclopedia (reference book)"})

It also existed as a play that Romana II once chose to attend over A Midsummer Night's Dream. She called it a comparatively "much more useful play, and much funnier too". (PROSE: A Midsummer's Nightmare ^[+]Loading...["A Midsummer's Nightmare (short story)"])

Professor Chronotis seemingly once replaced The Worshipful and Ancient Law of Gallifrey in the Panopticon Archives with a book, "an Earth classic by one of the greatest writers in that planet's history". Chronotis then went on to say "... terribly funny, terribly thoughtful, wish I could remember the name of it, something about thumbing a lift, and there were towels in it ... oh yes, of course, it's called The Hitch—" before being interrupted. (PROSE: Shada ^[+]Loading...["Shada (novelisation)"])

In the TARDIS library, Chris Cwej found a twentieth-century paperback that used the phrase "Mostly Harmless". This struck him as a good summation of how the Seventh Doctor and Roz Forrester had thought of him early in their travels, before they got to know him. Cwej was unsure whether the book had been fiction or non-fiction. (PROSE: Damaged Goods ^[+]Loading...["Damaged Goods (novel)"])

According to one account, the Tenth Doctor referenced Arthur Dent, a character from the novels, on Christmas Day 2006 due to wearing pyjamas like Dent did throughout his travels. (PROSE: Doctor Who: The Encyclopedia ^[+]Loading...{"name":"\"encyclopedia\"","page":"16","ed":"2011 reprint","1":"Doctor Who: The Encyclopedia (reference book)"}) However, other accounts asserted that Arthur Dent was a real individual whom the Doctor was acquaintances with. (TV: The Christmas Invasion ^[+]Loading...["The Christmas Invasion (TV story)"], PROSE: The Christmas Invasion ^[+]Loading...["The Christmas Invasion (novelisation)"], etc.)

Behind the scenes

These are allusions to the stage play and first novel of the Hitchhiker's Guide to the Galaxy multi-media series by Douglas Adams, which has multiple points of connection in- and out-of-universe with Doctor Who.