I'm surprised no one noticed the error right at the beginning of the article. The article says
Empire Online wrote:
The first original Star Trek tie-in novel (i.e. not the novelisation of an existing episode) was Spock Must Die! by sci-fi legend James Blish, published in 1970.
That's incorrect! The first tie-in novel was Mack Reynold's Mission To Horatius
You'll be thrilled to note that the recent SFX magazine special, "The A-Z of Star Trek", does give "Mission to Horatius" its due as the first ST novel. Well, kind of:
by Therin of Andor
, on Flickr
SFX magazine wrote:
"Well, it looks good... Trek's first spin-off novel was terrible - fortunately, the range didn't stop there."
The "T is for Tie-In Novels" feature encompasses pages 99-103.