One of his Riverworld books, Gods of Riverworld (Putnam, 1983), featured a distinctly Louise Brooks-looking character on the front of the book. And I seem to recall an interview or review which mentioned the author's fondness for the actress.
Here is the publisher supplied description of the book: Thirty-five billion people from throughout Earth's history were resurrected along the great and winding waterways of Riverworld. Most began life anew--accepting without question the sustenance provided by their mysterious benefactors. But a rebellious handful burned to confront the unseen masters who controlled their fate--and these few launched an invasion that would ultimately yield the mind-boggling truth. Now Riverworld's omnipotent leaders have been confronted, and the renegades of Riverworld--led by the intrepid Sir Richard Francis Burton--control the fantastic mechanism that once ruled them. But the most awesome challenge lies ahead. For in the vast corridors and secret rooms of the tower stronghold, an unknown enemy watches and waits to usurp the usurpers . . .