Robert A. Heinlein

"After the U.S. is conquered, an enclave of brilliant misfits leads a rebellion against near-impossible odds. The totalitarian East has triumphed in a massive invasion and the United States has fallen to a dictatorial superpower bent on total domination. That power is consolidating its grip via concentration camps, police state tactics, and a total monopoly upon the very thoughts of the conquered populace. A tiny enclave of scientists and soldiers...

Chronicles the life of a Temporal Agent sent on an intricate series of time-travel journeys designed to prevent future killers from committing their crimes. Now, on his final assignment, the Agent must stop the one criminal that has eluded him throughout time and prevent a devastating attack in which thousands of lives will be lost.

Set on the future earth. Johnny Rico is a young student dating a girl named Carmen. When Carmen decides she wants to become a citizen by joining the military, Johnny follows and joins as well. He soon realizes that he joined for the wrong reasons. Just as he is about to quit, an asteroid that originated from the orbit of planet Klendathu hits Buenos Aires and kills his family. From the bridge of the Fleet Battlestation Ticonderoga to the descolate...

"Once, military actions were entirely two dimensional, confined to the surface of land and sea, but then submarines and aircraft added a third dimension, vastly extended by spaceflight. Now, consider that if time travel is possible, the fourth dimension of time opens up new possibilities for combat, necessitating new defenses, new strategies and tactics. A battle that was once decisively won might be refought, or a narrow victory might be subtly tilted...

A handful of dedicated young soldiers must rise to the challenge of intergalactic warfare with a species of terrifying alien insects that threaten to eliminate the human race.