Ball, R. S. (1887). The story of heavens (3ª ed.). Casell and Company.
Cita Chicago (17th ed.)Ball, Robert Stawell. The Story of Heavens. 3ª ed. Casell and Company, 1887.
Cita MLA (9th ed.)Ball, Robert Stawell. The Story of Heavens. 3ª ed. Casell and Company, 1887.
Atenció: Aquestes cites poden no estar 100% correctes.