World Without Children and The Earth Quarter — Damon Knight

Two science fiction novels of tomorrowWorld Without Children: When humans can live for thousands of years, will it doom itself to extinction?The Earth Quarter: Why did the aliens on a remote planet keep all the humans locked inside a section of the city? Humans are used to be the top dog wherever they are--what are they going to do about it? (This novella also published alone as The Sun Saboteurs, and this collection of two stories also published as Two Novels.)