Del Ray is a sci-fi and fantasy publishing branch of Random House Publishing. In 1979 they attained the rights to publish Star Wars novel (just too-late to novelize the first film), and did so until the mid-1980s, at which point the license lapsed.
With the release of Star Wars: Episode 1, however, they re-attained the rights, and set right to work at publishing not just tie-in material, but their own mammoth series of expanded universe material (The New Jedi Order series, Fate of the Jedi, etc.), as well as publishing many reference and making-of books.
#1-9 -- Original license novels
#10-113 -- Second license novels
#114-146 -- Reference, art, and making-of books
