Gallagher, John S., III; Hoessel, John G.; Mould, Jeremy R.; Holtzman, Jon A.; Saha, Abhijit; Ballester, Gilda E.; Burrows, Christopher J.; Clarke, John T.;
ပြန်စစ်ပြီး။ Dreyer, J. L. E. (1888). "A New General Catalogue of Nebulae and Clusters of Stars, being the Catalogue of the late Sir John F.W. Herschel, Bart