débat Shapley-Curtis
1976 / The 'Great Debate': What Really Happened / M. A. Hoskin / Journal for the History of Astronomy 7 (1976) p. 169 [lien]
1990 / Through Rugged Ways to Galaxies / O. Gingerich / Journal for the History of Astronomy 21 (1990) p. 77 [lien]
1995 / The 1920 Shapley-Curtis Discussion: Background, Issues, and Aftermath / Virginia Trimble / PASP 107 (1995) p. 1133 [lien]