References

• Kenneth Glyn Jones, 1991. Messier's Nebulae and Star Clusters. 2nd ed, Cambridge University Press, p. 333. [ADS: 1991mnsc.book.....J].
• Jean Baptiste Joseph Delambre, 1827. Histoire de l'Astronomie au dix-huitièmme siècle [History of Astronomy in the Eighteenth Century]. Bachelier (Successor of Mme. Ve. Courcier), Paris. P. xxxix, 623-634.