Stanghellini, Letizia; Shaw, Richard A.; Villaver, Eva (Aralık 2008), "The Magellanic Cloud Calibration of the Galactic Planetary Nebula Distance Scale", The Astrophysical Journal, 689 (1), ss. 194-202, Bibcode:2003A&A...408.1029K, doi:10.1051/0004-6361:20031046.
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Stanghellini, Letizia; Shaw, Richard A.; Villaver, Eva (Aralık 2008), "The Magellanic Cloud Calibration of the Galactic Planetary Nebula Distance Scale", The Astrophysical Journal, 689 (1), ss. 194-202, Bibcode:2003A&A...408.1029K, doi:10.1051/0004-6361:20031046.