The Gentle Giants of Ganymede is a book published in 1978 that was written by James P. Hogan.
Thrice Upon A Time is a science fiction novel by James P. Hogan, first published in 1980. Unlike most other time travel stories, Thrice Upon A Time considers the ramifications of sending messages into the past and/or receiving messages from the future, rather than the sending of physical objects through time.
Discover the first three books in the ground-breaking 21st century hard-science fiction saga by James P. Hogan: INHERIT THE STARS The skeletal remains of a human body are found on the moon. His corpse is 50,000 years old, and nobody knows who he was, how he got there, or what killed him. THE GENTLE GIANTS OF GANYMEDE …