Tanar of Pellucidar Annotated and Illustrated

Tanar of Pellucidar is a novel by American writer Edgar Rice Burroughs, the third in his series set in the interior world of Pellucidar. It first appeared as a six-part serial in The Blue Book Magazine from March-August 1929. It was first published in book form in hardcover by Metropolitan Books in May 1930.The author's friend Jason Gridley is experimenting with a new radio frequency he dubs the Gridley Wave, via which he picks up a transmission sent by scientist Abner Perry, from the interior world of Pellucidar at the Earth's core, a realm discovered by the latter and his friend David Innes many years before.