רוברט סילברברג

In Illinois, the one-hundred-foot Cahokia Mound spreads impressively across sixteen acres, and as many as ten thousand more mounds dot the Ohio River Valley alone. The Mound Builders traces the speculation surrounding these monuments and the scientific excavations which uncovered the history and culture of the ancient …

The Time Hoppers is a science fiction novel by American writer Robert Silverberg, first published by Doubleday in 1967. The plot concerns Joe Quellen, a 25th-century bureaucrat charged with investigating "hoppers", travelers from the future whose presence in the past has been documented for hundreds of years, and his …

Thorns is a science fiction novel by American author Robert Silverberg, published as a paperback original in 1967, and a Nebula and Hugo Awards nominee.

Those Who Watch is a science fiction novel by Robert Silverberg, first published by Signet in 1967. The novel concerns a trio of alien explorers, each one surgically altered so that they outwardly appear human, who find themselves separated, and permanently stranded on Earth, after their ship explodes while hovering …