Because many of my titles are reprints, and subject to copyright restrictions where they are not public domain, I use an app to block visitors from particular titles in certain locations. Many of my titles are only available to U.S. readers, for example, while there are a handful that are not available to U.S. readers. (That's why my title count here is about 250, but you're unlikely to see all 250 titles.)
I have it set up so that if you see a title now, you should be able to buy it. (If that's not the case, please let me know through my Facebook page. I had to turn off comments here due to high spam rates.) Copyright restrictions vary around the world, but if I see a buyer from a country I haven't accounted for (that has a life + 50yrs copyright length), I'll try to go back and add more permissions.