Alien Encounter: A Scientific Novel, Edition 2

Life in the Universe: Expectations and Constraints, Edition 3

Life in the Universe: Expectations and Constraints, Edition 2

Cosmic Biology: How Life Could Evolve on Other Worlds

The Extraterrestrial Encyclopedia

We Are Not Alone: Why We Have Already Found Extraterrestrial Life

Megacatastrophes!: Nine Strange Ways the World Could End