a real world point of view
Doctor Who reference books are any books that contain reference material concerning Doctor Who and/or the Doctor Who universe. These cover a range of reference material both fictional and nonfictional, such as; programme guides, "Making Of" books that cover behind the scenes information, in-universe books detailing information that was not covered within the narrative and purely illustrated books that showcase a particular artist's work.
During the 1970s these books were almost entirely published by Target Books, who also published the novelisations of Doctor Who. These publications were combination of behind the scenes or "Making Of" books and themed books, concentrating on "Monsters" or particular aliens such as Terry Nation's Dalek Special and The Adventures of K9 and Other Mechanical Creatures.
The 1980s can be seen as the real beginning of Doctor Who non-fiction publications, with several large format books being published during this time. Many of these were written by Peter Haining, who contributed five lengthy books concerning the production and history of Doctor Who.
1983 saw the debut of the first book providing analysis of Doctor Who; Doctor Who: The Unfolding Text was a media text for teachers and students, discussing the narrative structure of Doctor Who and the production techniques at work.
During the 1990s is when the books analysing Doctor Who began to be more frequently published. With the range and availability of the Doctor Who on video tape and DVD this was a period when most of the stories could be re-watched with ease. The popular Doctor Who Handbook range published by Virgin Books covered each Doctor's era in great detail and remain highly regarded as reference works to this day.
In the early 2000s books such as Mad Norwegian Press's I, Who range of were published breaking down and analysing all of Virgin Books' and BBC Books' novel ranges and most of Big Finish Productions' prose and audio ranges. During this time there were a few non-fiction books published by BBC Books, both non-fiction such as Doctor Who: Regeneration which contained detailed information surrounding the attempt to bring Doctor Who back in in the 1990s, and the subsequent production of the 1996 TV movie and also the fictional though non-narrative book the Dalek Survival Guide.
There both fictional, though non-narrative works such as Doctor Who: Monsters and Villains and also nonfiction books like Doctor Who: The Inside Story and for the first time since 1996's publication of Doctor Who: The Script of the Film, Doctor Who: The Shooting Scripts was published which contained all the scripts from the series that had aired that year.
During the latter part of of the 2000s it continued to be a mix of reference books that were fictional and nonfictional, though the fiction-based books outweighed the non-fiction works.
Beginning in 2005, and with the launch of the BBC Wales produced new series, BBC Books began a series of illustrated paperback guides to both 'classic' and 'new' Doctor Who adventures, the first release was Doctor Who: Monsters and Villains. Each had a specific theme and title, with a similar cover format across each release. They were lavishly illustrated throughout and cost £7.99 (UK).
Two publications of BBC Books' themed illustrated guides were released in 2009.