That can't be right, can it? There were about 90 numbered TOS books, 40-ish TNG books, dozen or so VOY books, maybe 20 or 30 DS9 numbered books. That gets you over that number by itself, and that's not even counting the several years since they stopped numbering, which has gotta count for another 40-50 books anyway. I've got way more than 150 unique star trek books on my shelf alone, and I'm probably missing a few.
Do you mean just TOS books?
Sorry, of course I meant TOS-Books.
Summary of all Series is 552 at the moment.
Corrected my above post for clarification.