During the decade we were out of print, we know of several used book sellers who hand sold the then-three Liaden books, building recognition and awareness of the series. In a very real way, used bookstore sales made it possible for us to come back from the dead.

I suspected that was the case, but didn't want to assert it as fact.

I think a very similar thing happened with the works of Barry Hughart, Patricia Wrede and Caroline Stevermer, Hope Mirrlees, and probably a few others I'm not remembering off the top of my head. Word-of-mouth can only work when there are physical copies of the books to accompany it, and libraries generally don't acquire out-of-print books they don't already own.

I hope such a revival may be happening now for the out-of-print works of Walter Jon Williams, Alexei Panshin, Lawrence Watt-Evans, and others. And used books will be necessary for those, too.