I shouldn't be wasting my time reading this thread, let alone posting to it, but since there seem to be so few people here who have actually read any classic science fiction ...

"To Serve Man" was written by Damon Knight. The Twilight Zone episode was a dramatization of his short story.

Heinlein not only popularized the expression TANSTAAFL, but he invented it in his novel The Moon Is A Harsh Mistress. (If anyone knows of a usage of the term that predates the novel, please speak up. Every reference to the term that I've seen, including an Economics textbook named TANSTAAFL, credited it to Heinlein.)

In case there are any SF fans out there who remember the days before the FIAWOL/FIJAGDH controversy, here's a line from an Asimov short story:

"Not blood, but high grade machine oil."