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I. O. Drozdovsky et I. D. Karachentsev, « Photometric distances to six bright resolved galaxies », Astronomy and Astrophysics Supplement, vol. 142, , p. 425-432 (DOI10.1051/aas:2000155, Bibcode2000A&AS..142..425D).
Rosa M. González Delgado, Enrique Pérez, Clive Tadhunter, José M. Vilchez et Rodríguez-Espinosa José Miguel, « H II Region Population in a Sample of Nearby Galaxies with Nuclear Activity. I. Data and General Results », The Astrophysical Journal Supplement Series, vol. 108, no 1, , p. 155-198 (DOI10.1086/312951, Bibcode1997ApJS..108..155G).
Abraham Mahtessian, « Groups of galaxies. III. Some empirical characteristics », Astrophysics, vol. 41 #3, , p. 308-321 (DOI10.1007/BF03036100, lire en ligne, consulté le ).