Intelligent Life in the Universe by Carl Sagan & I. S. Shklovskii

In Sagan's description of his remarkable collaboration with Shklovskii, conducted entirely by mail with the Russian scientist in the Soviet Union and Sagan in the U.S., he explains they were never able "to discuss the present edition in person. 'The probability of our meeting is unlikely to be smaller than the probability of a visit to the Earth by a extraterrestrial cosmonaut," Shklovskii once wrote him. Throughout the book, Sagan adds "about as much material as there was in the work initially" and was the sole author of "the figures and captions."

A gorgeous paperback edition by Holden Day publishing.