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COLLINDER, Per. On Structural Properties of Open Galactic Clusters and their Spatial Distribution. Catalog of Open Galactic Clusters. S. B1-B46. Annals of the Observatory of Lund [online]. 1931 [cit. 2017-10-04]. Čís. 2, s. B1-B46. Dostupné online. Bibcode1931AnLun...2....1C. (anglicky)
MELOTTE, P. J. A Catalogue of Star Clusters shown on Franklin-Adams Chart Plates. S. 175. Memoirs of the Royal Astronomical Society [online]. 1915 [cit. 2017-10-04]. Roč. 60, s. 175. Dostupné online. Bibcode1915MmRAS..60..175M. (anglicky)
seds.org
spider.seds.org
SEDS Messier Objects Database: Revised NGC Data for NGC 2099 [online]. [cit. 2017-10-04]. Dostupné online. (anglicky)
messier.seds.org
SEDS Messier Objects Database: Messier 37 [online]. [cit. 2017-10-04]. Dostupné online. (anglicky)