DS9, yes, but TNG has also included Losing the Peace, Indistinguishable from Magic, and Cold Equations.
I didn't really see Indistinguishable from Magic
as a pure TNG novel
What does "pure TNG" mean?
An actual TNG novel I think, not one that just uses the name and has the Enterprise-(D or E) and crew show briefly.
case in point despite Double or Nothing being labeled as a TNG novel and having Riker and Picard in it it was really a New Frontier novel.
Just like how Indistinguishable from Magic
seems more like a novel staring the U.S.S. Challenger and its crew, heck if not for the ending this would seem like the first book in a new novel series.