In the Black Zone; or, Frank Reade, Jr.'s Quest for the Mountain of Ivory
From Author Wars - https://authorwars.com/books/in-the-black-zone-or-frank-reade-jrs-quest-for-the-mountain-of-ivory-2433236.html
From Author Wars - https://authorwars.com/books/in-the-black-zone-or-frank-reade-jrs-quest-for-the-mountain-of-ivory-2433236.html