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.

Voyage from Yesteryear is a 1982 science fiction novel by James P. Hogan.