The Caldwell objects and how to observe them - Mobberley, Martin-; SpringerLink (Online service) (New York, NY : Springer-Verlag New York, 2009)
Keywords: Astronomy -- Observers' manuals; Astronomy -- Charts, diagrams, etc; Galaxies -- Charts, diagrams, etc; Stars -- Clusters -- Charts, diagrams, etc; Nebulae -- Charts, diagrams, etc; Astronomers' observing guides; Physics; Astronomy, Observations and Techniques; Popular Science in Astronomy