His Physical studies of planets, 1960.

Washington post, 21 December 1996, p. A 12 (died at age 62; astronomer; at age 25, doctoral thesis, Physical studies of planets)

Carl Sagan's cosmic connection, 2000: CIP t.p. (Carl Sagan) pub. info. (Carl Edward Sagan; b. Nov. 9, 1934; d. Dec. 20, 1996)

Wikipedia, September 8, 2015 (Carl Sagan; Carl Edward Sagan (November 9, 1934-December 20, 1996) was an American astronomer, cosmologist, astrophysicist, astrobiologist, author, science popularizer, and science communicator in astronomy and other natural sciences; born Brooklyn, New York; died Seattle, Washington; spent most of his career as a professor of astronomy at Cornell University, where he directed the Laboratory for Planetary Studies)

Biblioteca del congreso (Estados Unidos), 01 junio 2018: catálogo electrónico https://goo.gl/bmFKPd