Help! I want to find this book!?

[AnnabethChase5450]

I don't think such a book exists...Wikipedia isn't always reliable...

This is a booklist of Robert Sheckley's works. It's not on it.

 

[Cat]

I read on wikipedia that the mangaka for Gantz was inspired by Robert Sheckley's novel Time Murderer, I've look everywhere for this book and I can't find it! Any help?