Robert A Heinlein

E.C. "Scar" Gordon, a Vietnam veteran, answers an ad promising adventure and meets a mysterious beauty who transports him to another world.

A high school senior goes through the gate to an unknown planet for a two-to-ten day final exam in Advanced Survival, and realizes, after a period of fighting the elements and wildlife, that something has gone wrong with the gate and what was a brief survival exam is an endless struggle for life.

A beautiful interplanetary agent, a glorious product of genetic engineering, operates from and over a near-future Earth.

Three teenagers and an older scientist develop their own atomic rocket, solve their own space problems and blast off for the moon in spite of mysterious setbacks.

Two young lovers are forced apart by pride, power, and the immensity of interstellar time and space, in an authorized version of an unfinished novel by Hugo Award-winning late science fiction master Robert Heinlein.

Lazarus Long, member of a select group bred for generations to live far beyond normal human lifespans, helps his kind escape persecution after word leaks out and angry crowds accuse them of withholding the "secret" of longevity. Lazarus and his companions set out on an interstellar journey and face many trials and strange cultures, like a futuristic Odysseus and his crew, before returning to Earth.