TARZAN AND THE LION MAN EDGAR RICE BURROUGHS ACE F-212
John Carter of Mars
The Chronicles of Amber by Roger Zelazny. The stories take place in two, true worlds: Amber, and the Courts of Chaos. Other worlds are "shadows" of the tension between the two true worlds. The Courts of Chaos is situated in Shadow at the very edge of Chaos itself. Royals of Amber who have negotiated the Pattern can travel freely through the shadows. By shifting between shadows, one can appear to alter reality by choosing which elements of which shadows to keep, and which to move between.
My favorite Heinlein book: "Number of the Beast"
Anyone else remember reading the Lensman Series by E.E. doc Smith?