Variable Features on Mars: Preliminary Mariner 9 Television Results. Sagan, C. ; Veverka, J. ; Fox, P. ; Dubisch, R. ; Lederberg, J. ; Levinthal, E. ; Quam, L. ; Tucker, R. ; Pollack, J. ; Smith, B. Abstract Publication: Bulletin of the American Astronomical Society Pub Date: June 1972 Bibcode: 1972BAAS....4..313S