Starfleet Academy (TOS) novels 3

A young Spock travels with Sarek to a peace conference aboard the Enterprise under Captain April, and has to decide between the Vulcan Science Academy and Starfleet while rebels target his family.

Medical student Leonard McCoy loses his winter break because of an upstart cadet named Kirk, and ends up on disaster relief on an earthquake-hit planet with a Vulcan named Spock.

Cadet Kirk, Ensign Spock and intern McCoy are forced down at a remote outpost by pirates waiting for the famous scientist Richard Daystrom, and Kirk decides to stop them himself.