There are 3 unique codex entries in the Achievement: Datacrons section on Quesh. They are accessible to all players regardless of class or faction.
Galactic History 58: Ulic's Trials is obtained from interacting with the +4 Orange Mastery datacron.
Codex type: Achievement: Datacrons | Faction: Both | Class: All
Associated Achievement: Quesh Datacron Master
Galactic History 59: Aleema's Fate is obtained from interacting with the +4 Green Endurance datacron.
Codex type: Achievement: Datacrons | Faction: Both | Class: All
Associated Achievement: Quesh Datacron Master
Galactic History 60: The Destruction of Ossus is obtained from interacting with the +4 Red Mastery datacron.
Codex type: Achievement: Datacrons | Faction: Both | Class: All
Associated Achievement: Quesh Datacron Master