Are you able to provide any examples?
"Over a Torrent Sea" reviews:
I liked it!
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 in 1967.
They simply missed the adjective "adult". "Spock Must Die!" was the first adult original "STAR TREK" novel, and "Mission to Horatius" was marketed to children
. Today it might have been labeled for "Young Adults".