Traveller was first published 1977, and was inspired by even older science fiction. While this means that the computer rules used in traveller might feel a bit obsolete, it also means that for some of the books it was inspired by, the copyright has expired. (The computer rules are quite easy to ignore or modify anyway, so that doesn’t matter much.)
Here is a suggestion of five books for you to download:
In Space Viking, there is a group of planets called Sword Worlds that are named after legendary swords. Doesn’t that seem familiar… The image below of the spherical ships is from the book. They look a lot like the Mercenary Cruisers from traveller.
Jason dinAlt is the hero of the Deathworld books. In the Traveller Supplement 1, 1001 Characters, you can find his stats as hero #3, the Rapscallion Gambler. Jason dinAlt is skilled in gambling and also has a psionic talent, that can help his gambling. In Traveller, gambling is a skill, and psionics isn’t impossible.
Jame Retief is a Diplomat for the Corps Diplomatique Terrestrienne. In Traveller Supplement 4, Citizens of the Imperium you can find his stats as hero #5.
Image from Project Gutenberg. Copyright expired.