Pellucidar — by Edgar Rice Burroughs

Order	Book	Date	Rating
1	At the Earth's Core		4
2	Pellucidar	1915	4
3	Tanar of Pellucidar	1929	4
4	Tarzan at the Earth's Core	1922	4
5	Back to the Stone Age // Seven Worlds to Conquer	1936	4
6	Land of Terror	1944	4
7	Savage Pellucidar	1941	4