I have a lot of trouble with the 'hollow earth theory' itself, because years ago in my hand I had an article that showed where the original article came from, and how all the subsequent references to it traced back to the same hoax- a hoax that originated in a specific place planted by someone in a periodical, who had ties to a religious organization tasked with disseminating the theory. Unfortunately, I didn't put it in a place where I can find it (it's in my office/library, under piles and piles of old books and magazines) and I haven't been able to find it. It cites specific publications and presents a timeline, showing that it is indeed a hoax- a deliberate attempt to refute reasonable scientific knowledge about the earth and its' stucture.