Reddit reviews Star Trek: The Classic Episodes Hardcover

It was this: https://www.amazon.com/Star-Trek-Classic-Episodes-Hardcover/dp/0385365241

I don't mean to make it sound like hard scifi literature, but it was far less campy and far more serious than the series. There were also some minor but significant changes made between these scripts and the show.

You could tell that some of the episodes were slightly dumbed down for TV. In Operation: Annihilate! for example, it wasn't intense light that killed the beasties, but rather the magnetic flux of the star. They also realized that there was no way a starship had the power to overwhelm the natural magnetic field of a planet, so they found an alternative you'd never expect of the Starfleet we know. They were also on the verge of sterilizing Deneva via orbital bombardment to contain the epidemic before finding this solution.