Another of the few Trek books I purchased during the '90s was The Star Trek: The Next Generation Companion by Larry Nemecek.
This book has been issued in three editions to date; mine is from the first edition which was published in November 1992. The first edition contains episode summaries up to and including season 5. Subsequent editions added summaries for the remaining two seasons of the show and the TNG movies. My copy is from the first printing.