fictional

Invented, as opposed to real.

Romeo and Juliet are fictional characters.

The janitor's account of the crime turned out to be entirely fictional.

Containing invented elements.

The Simpsons is a fictional television show.

Including both factual and fictional books would have reduced the value of the study; it would have made the content too heterogeneous for the drawing of significant conclusions.

Occurring in fiction.

Tunnels often feature in fictional journeys, so I will end with quotations from a fairly recent novel, Howard Spring's "Fame is the Spur", published in 1940, in which there is a journey from Manchester to Bradford via the Calder Valley route: "Ay, we're going through Todmorden. We'll soon be in t' tunnel, and when we get to t' other end we'll be in Yorkshire," and "Ah think this is t' filthiest tunnel in t' world."