Herschel, William (1802). "Catalogue of 500 New Nebulae, Nebulous Stars, Planetary Nebulae, and Clusters of Stars; With Remarks on the Construction of the Heavens". Philosophical Transactions of the Royal Society of London92: 477–528 [481]. Bibcode1802RSPT...92..477H. JSTOR107131.
jstor.org
Herschel, William (1802). "Catalogue of 500 New Nebulae, Nebulous Stars, Planetary Nebulae, and Clusters of Stars; With Remarks on the Construction of the Heavens". Philosophical Transactions of the Royal Society of London92: 477–528 [481]. Bibcode1802RSPT...92..477H. JSTOR107131.