Pretty versatile writer. In sort of the same vein, I read everything by Edgar Rice Burroughs, who is known mainly for Tarzan, but also wrote several great fantasy series like John Carter of Mars and the Venus and Pellucidar series. In Pellucidar, the earth is hollow with a mini-sun suspended in the middle. Gravity is in the world's crust, so the denizens of Pellucidar walk on the inside of the crust and the horizon stretches upwards for them. Gateways are at the poles and some dinosaurs which passed through still live. Edgar's books were always next to William S. Burroughs' books, like Naked Lunch or Junky. Picked one up by mistake as a 14 year old, what a thrill!