UK-based on-line bookseller The Book Depository is a good resource for finding publications that are either out of print or not widely available in the US.
Check out the “Watch People Shop” feature. Tracing tabs on a world map as they ping-pong between recent sales in real time in entrancing. Someone in California just bought African Animal Stickers. Then someone in South Africa bought The Last Snake Man. Someone in Canada bought The Stars, and someone in Australia bought Bright Star a few minutes later. It’s like six degrees of book separation.