oh yeah. if you take in account his academia writings which is really impressive, he wrote A LOT. What I read was basically all the books in the robots-empire-foundation series...maybe 25 books?

You can search online for more covers "nemira covers" or smth. But here's the wow part: all these covers were designed by the same guy: Tudor Popa!!

Please re-check the post.I've added a few other covers