The text for my sections of AST 115 is
Life in the Universe: The Abundance of Extraterrestrial Civilizations (2008) by Pierce.
Paperback copies are available at the campus bookstore or online through the publisher (BrownWalker Press), Amazon, and Barnes & Noble (see links at the BrownWalker site).
Electronic book editions (eBooks) are available at Diesel eBooks and Powell's Books.
ISBN information for this text: