I use Books on Board for my ebooks, and I daily search for certain authors.
One of these authors is Donald Hamilton, aka Matt Helm series.

Well, BoB has one of the Donald Hamilton novels, not Matt Helm, for sale now. Following the publisher info, it came from Hard Case Crime.
I went to the web site and was delighted with what is being published. Had not seen it before.
I am hoping with all fingers crossed that they will carry the Matt Helm series. I couldn't find which publishers ended up with the Matt Helm series after all this time and all the buyouts. If anyone knows, please pass it on.
AJ