by Leo P. Kelley (1979)
Brett Kinkaid, serving a life sentence on Earth, the prison planet, is offered freedom if he rescues a kidnapped young woman from the star Alba.
Andre Norton
The tramp-freighter spaceship Solar Queen had exclusive trading rights to Sargol and its fabulous gems. But the crew's bravery and resourcefulness strained to the breaking point as they met Sargol's three challenges: the enigmatic obstinancy of the planet's catlike natives, ruthless incursions of an illegal competitor, and worst of all -- an invisible, undetectable stowaway whose presence branded the Solar Queen a plague ship...off limits to the rest of the galaxy!
L. Ron Hubbard
When the Asiatic Federation splits off from the oppressive United Continents with the help of a device that keeps them separated, space navy lieutenant George Marquis Lorrilard's greedy actions are on a course to change the universe's fate.
(by) Sylvia Engdahl
A young woman is sent into danger on a planet poised on the brink of nuclear war, forbidden to interfere with its people's natural course of evolution or to reveal her alien origin. Her fellow-agent is not properly trained to work in the field and his compassion may lead him to intervene, thereby unintentionally bringing about the very disaster that he is trying desperately to prevent. She faces an agonizing choice: side with a renegade agent, ot stop him at any cost. Although this novel has the same heroine as *Enchantress from the Stars* it is not a sequel but a completely independent story not intended for readers below high school age. The 2003 edition contains significant updating and should be read in preference to earlier editions.
Susan Jane Bigelow
What will you give up to change the world? It's not about her sisters anymore; it's not about her home or her family. It's not about aliens, conspiracies, or abandoned planets. It's about making the world work again, the way it was supposed to. And nothing will stop Violet Grayline now that she's started.