Recommended reading - The Star Trek Reader I, by James Blish (1976):

The Star Trek Reader I

By James Blish.

Published by E P Dutton.
First Edition.
Published 1976.
Hardcover.
ISBN-10: 0841504679
ISBN-13: 978-0841504677

Description:

Episodes from the popular TV series, many of which have been selected by fans themselves, have been adapted into short stories.